I Found 21 SECRET Places in NSW That You've Never Heard Of!

New South Wales is the most populated state in the country and in its southern corner contains one of the largest cities in the southern hemisphere. Five and a half million people in Sydney alone. Highways, infrastructure, council regulations covering everything from bin placement to the colour of your front door. The entire apparatus of modern Australian administrative life Embedded in this landscape, within an hour or two of the city in most cases, sometimes less, there are structures that look like they were left behind by a previous civilisation. Not ghost towns in the outback sense, not scenic waterfalls and viewpoints from the tourist brochures. Actual infrastructure, factories and bunkers and asylum wards and retorts and shipwrecks and tunnel systems that most people drive past their entire lives without knowing exist. Places that require no particularly exotic location to reach and yet produce in the person who finds them an absolute conviction that they have stumbled into somewhere they weren't supposed to know about. So subscribe and let's start. Number 21, the Homebush Bay Shipwrecks Sydney Olympic Park, Western Sydney. Let us begin somewhere that is genuinely within the city, visible from apartment windows, accessible on foot, listed in official tourism material and yet somehow remains unknown to the majority of Sydney siders who live within 10 kilometres of it. Homebush Bay on the south bank of the Parramatta River in Western Sydney contains a small fleet of abandoned ships. Not sunken ships, not ships on the bottom of the harbour, ships sitting in the shallows of the bay, half submerged, rusting and in the most famous case entirely overtaken by a forest of mangrove trees that has grown straight through the hull and out the other side. The SS Airfield is the star of this collection. Built in the United Kingdom in 1911 as a steel hold steam collier weighing 1140 tonnes, it was registered in Sydney in 1912 and spent the following six decades transporting coal and oil along the New South Wales coast. During the Second World War it was requisitioned by the government to transport supplies to American forces stationed in the Pacific. After the war it returned to commercial service, eventually passing through several owners before being retired in 1972 and brought to Homebush Bay which at the time functioned as a ship breaking yard. The intention was to cut it up for scrap. The intention was not realised. The SS Airfield sat in the shallows of the bay while the ship breaking yard wound down its operations and the other vessels around it were dismantled. At some point, nobody is entirely sure how, mangrove seeds arrived on the hull. They germinated. They grew. Over the decades that followed the trees grew into one another and through the rusted steel and over the corroded superstructure until the hull of the former cargo ship became a small floating forest, a dense dark green island of vegetation sitting incongruously in the suburban bay at a ship's And scientists note that the mangroves have essentially created a functioning micro-ecosystem, fish shelter in the shade beneath the hull, crustaceans colonise the submerged sections, birds nest in the branches. The bay also contains three other wrecks, the SS Mortlake Bank, HMAS Karangi and SS Heroic in various states of decomposition. All of them are The SS Airfield became particularly celebrated after the Sydney Olympic Games brought development and waterfront promenades to the area, giving apartment residents and parkland visitors a direct view of a ship that the 20th century forgot to dismantle. As of today, it is the most photographed abandoned vessel in the country. Asked this is what happens when neglect takes long enough, it stops being a failure and becomes a landmark. The Mittagong Maltings, Southern Highlands, New South Wales. About one hour and 40 minutes south of Sydney, in the town of Mittagong in the Southern Highlands, there stands a large complex of industrial buildings that most people driving through on the Hume Highway would clock as some sort of old factory and think nothing further about. It is in fact one of the most historically significant and visually striking abandoned industrial sites in the state. The Mittagong Maltings complex was built in 1899 to produce malt for the Tooth & Company Brewery, at the time one of the largest beer producers in New South Wales, and it operated continuously for the better part of a century. At its height, the complex was a major regional employer, its kilns and drying floors converting barley into malt that was then transported to Sydney for the brewing process. The main building is a substantial brick structure with a distinctive roof profile, and the collection of buildings that surrounded and supported it formed a self-contained industrial precinct in the middle of a Southern Highlands market town. For decades it was simply there, part of the town's backdrop, taken for granted. The decline of Tooth & Company in the latter part of the 20th century, the company was eventually absorbed by Carlton and United Breweries, which itself went through several rounds of ownership consolidation, meant the Mittagong complex lost its purpose. A destructive fire in the 1980s damaged parts of the main building significantly. Ori the complex was ultimately abandoned, and for the following decades it stood in an increasingly deteriorated state while heritage listing applications and development proposals came and went. The creaking brick structures, their walls crumbling, and their windows long since empty of glass became a fixture of the regional urbex community, and a subject for photographers drawn by the combination of age, industrial architecture, and visible decay. The site has been the subject of repeated proposals for residential or commercial redevelopment that have not yet materialized. As of the time of making this video, it remains behind a security fence, viewable from the street, frozen in a state of advanced industrial decline. 19. The Noon's Shale Oil Ruins, Wolgan Valley, Blue Mountains The Wolgan Valley is a remote gorge in the western Blue Mountains, about four hours from Sydney by road, and at the bottom of it accessible by a drive through some of the more spectacular sandstone country in New South Wales. Are the ruins of one of Australia's most ambitious and ill-fated industrial experiments. The Noon's Shale Oil Works was established in 1906 by the Commonwealth Oil Corporation to extract kerosene and other petroleum products from the oil shale deposits that had been discovered in the valley's rock formations decades earlier. A town was built in the valley to house the workers. A 50-kilometre railway line was constructed through extremely difficult terrain to connect the works to the main government railway. Retorts were built, pipelines were laid. By 1907, the town's population had reached around 800 people. The operation was never commercially viable. The shale in the Wolgan Valley was low-grade, the costs of processing and transportation through the mountains were prohibitive, and the availability of cheaper imported crude oil made the economics of domestic shale production increasingly difficult to justify. The works limped along through the 1910s and 20s, periodically closing and reopening as prices shifted, and finally shut for good in 1932. The population departed. The railway was eventually dismantled in the 1940s, its rails removed for scrap. The retorts, the large brick structures in which the shale was heated to extract its oil, were left standing in the valley. Today, the ruins of the Noon's Shale Oil Works consist of a collection of brick and concrete structures of considerable size, slowly being absorbed by the subtropical vegetation of the valley floor. The retorts stand in rows, their original function still clearly legible in their form, surrounded by the debris of a century of neglect and the vigorous growth of the Blue Mountains bush. The site requires a full day's travel from Sydney and a walk of several kilometres from the camping area to reach, which is why most people have never heard of it. Those who do make the trip describe the experience of finding a large-scale industrial complex in the middle of a national park wilderness as producing a quality of cognitive dissonance that no amount of prior research entirely prepares you for. Number 18. The Noon's Glow Worm Tunnel. Wollemi National Park. This is connected to the previous entry and deserves its own section. The 50-kilometre railway that was built to service the Noon's Shale Oil Works included a tunnel on the plateau above the Wolgan Valley constructed to allow the railway to descend from the Noon's Plateau down toward the works in the valley below. The tunnel was cut through the sandstone of the 1940s and the rails removed, the structure was simply abandoned. The sandstone retained the moisture of the escarpment. Darkness and humidity filled the passage. Fungus gnats found it. Their larvae, the glow worms, colonised the ceiling. The Noon's Glow Worm Tunnel is now one of two abandoned railway tunnels in New South Wales that contain large colonies of bioluminescent glow worms and it is the more dramatically located of the two. The walk to reach it from the Noon's Plateau takes visitors across a high plateau of wildflower heath and heath scrub before the ground drops and the sandstone country closes in and the tunnel entrance appears in the side of the cutting. The tunnel is several hundred metres long, long enough that the entrance becomes a distant point of grey light and the ceiling above becomes dark enough that the glow worm colonies are clearly visible. A constellation of cold blue-green points of light extending overhead into the blackness, indistinguishable at first glance from a photograph of the night sky. The water that runs through the tunnel is typically ankle deep which is why the standard advice is to wear boots you don't mind ruining. There is no lighting, there are no handrails, there are signs asking you not to touch the walls. Number 17. The Hellensburg Glow Worm Tunnel, south of Sydney. This is the second of the two NSW Glow Worm Tunnels and it has the advantage of being considerably closer to Sydney, about an hour south by car near the town of Hellensburg in the Illawarra region. The Metropolitan Tunnel, as it is formally known, was opened on the 1st of January 1889 as part of the Hellensburg Railway Station's original configuration. It was 624 metres long and connected the local coal colliery with the station as a way to transport mining produce uphill. The station and both its tunnels were closed in 1915 when the railway line was duplicated and rerouted to simplify the Sutherland to Wollongong journey. With the tunnel no longer in use, the Metropolitan Colliery converted it into a reservoir, installing a concrete plug at the southern end in May 1928 to control the flooding. And then, for the better part of a century, it sat. The entrance became overgrown. The track was buried under soil and debris. In April 1995, Metropolitan Colliery cleared the northern entrance and the old platform, including bricks from the original station, was uncovered. By 2001, Hellensburg Landcare had received a centenary of federation grant and restored parts of the station. The original track was relayed. The Hellensburg station sign was restored. And the glow worms, who had been quietly colonising the ceiling of the dark, damp tunnel for decades, were discovered to have established one of the largest colonies in New South Wales. Today, the walk to the tunnel entrance takes visitors through temperate rainforest before opening into a sandstone rock corridor. Inside, the 624 metre tunnel floods regularly, sometimes to ankle depth, sometimes considerably higher. And the darkness is complete enough that the glow worms overhead are visible immediately once your eyes adjust. The tunnel is managed by Hellensburg Landcare and access has been periodically restricted to protect the colony from the human traffic that viral social media exposure inevitably generates. A man named Robert Hallis was killed by a train inside the tunnel in 1895, which is the kind of historical detail that the area's paranormal enthusiast community finds considerably more interesting than its railway historians do. Number 16. The Bankstown Bunker, Bankstown, Sydney. Under a small park in the southwestern Sydney suburb of Bankstown, buried beneath townhouses and landscaped grass in a residential street, there is a World War II bunker that most people have no idea exists. The Bankstown Bunker, formerly known as the former Sydney Air Defence Headquarters, was constructed in late 1942 at a cost of £30,579 and it was commissioned in January 1945 as the Operation Centre for Number One Fighter Sector, RAAF, the unit responsible for the aerial defence of New South Wales against Japanese attack. The bunker's walls were one and a half metres of reinforced concrete, thick enough to withstand a near miss from a reasonably sized bomb. Inside, it contained three fixer stations and one homing station, in switchboards directing up to 50 telephone lines, connecting it to radar stations and observer posts up and down the NSW coastline, a code room, plotting rooms, a radio transmitter room and two escape tunnels. The main operations room was a two-storey space at the centre of the structure, its focal point a 24-foot by 18-foot map of the Southwest Pacific Theatre, on which the positions of Allied and enemy aircraft were tracked by women from the Women's Auxiliary Australian Air Force, who had been transported to the site in buses with blacked-out windows. The bunker operated from January 1945 until 1947, at which point the war was over and the RAAF had no further use for it. A fire in August 1971 destroyed the interior. The above-ground support buildings were demolished in a 1976 redevelopment of the site. Townhouses were built over the top. The entrance was sealed. The hillside was landscaped. Today there is a small reserve in Taylor Street, Bankstown, and beneath that reserve is a sealed concrete bunker that once controlled the air defence of the entire state, its existence known primarily to local historians, a few railway enthusiasts who have researched it from old records, and the people who happen to watch a particular episode of the television programme Burke's Backyard, in which Don Burke entered through an air vent. There are also persistent rumours of a tunnel approximately four miles long connecting this complex to another facility, the destination of which has never been publicly confirmed. The rumours have been documented and remain, as far as anyone publicly knows, unverified. Number 15. The St James Station Tunnels, Sydney CBD. Directly beneath the streets of the Sydney CBD, under the railway station at St James, in the city's legal and cultural precinct, there are tunnels that were built for a railway line that was never completed. The St James Station itself was opened in 1926 as part of the City Circle Railway, but the platforms and tunnels beneath it were designed with a future extension in mind. A line that would run south from the city under Elizabeth Street and eventually connect to a second city circle. The tunnels for this extension were bored during the construction of the station and simply left when the extension was deferred, then quietly forgotten as subsequent generations of transport NSW planners worked on different priorities. If this video is giving you the productive unease of realising how much infrastructure exists beneath the city you live in, subscribe to show that these videos actually help and make sense. The tunnels extend south from the station platforms under the CBD, broad enough to accommodate full-size railway cars, entirely complete as tunnels and entirely empty as railway infrastructure. During the Second World War, they were pressed into service as a plotting room and command centre for air defence operations. The same role that the Bankstown Bunker was eventually built to fulfil more securely. The Americans used them as an operations facility for a period, they were then sealed and largely forgotten. In recent decades, as various proposals have been made to repurpose them as spaces for art, events, emergency infrastructure or additional transport capacity, none has progressed to construction. The tunnels remain beneath the city, immaculately useless, known primarily to transport NSW employees, railway historians and people who read too many heritage reports. Number 14. The North Head Fortifications, Manly. Sydney Harbour has been defended in various ways since European settlement and the evidence of those defensive efforts is distributed across the headlands in a collection of fortifications, tunnels, gun emplacements and underground facilities that most harbour visitors sail past without knowing they're there. The North Head Fortifications at Manly are among the most extensive of these. The fortifications at North Head were established in 1936 as part of a 300 kilometre coastal defence system that ran along the entire NSW coastline during the Second World War. Built on the northern entrance to Sydney Harbour, the North Fort Battery featured two 9.2-inch calibre guns capable of firing a projectile a distance of 26.5 kilometres, meaning they could engage a hostile vessel before it came within conventional range of the harbour. The guns were serviced by a network of underground tunnels connecting the gun emplacements to magazines, crew quarters and a plotting room that was built eight metres underground and constructed to be both concrete reinforced and bomb-proof. The plotting room received target coordinates from an observation network along the coast and relayed firing instructions to the gun crews above. The fortifications were decommissioned in 1952 after the development of long-range aircraft and guided missiles rendered coastal gun batteries obsolete. They were subsequently largely forgotten, buried in the scrubby heathland of Sydney Harbour National Park, their tunnel entrances overgrown, their gun emplacements slowly settling into the sandstone. Today the site is accessible via Sydney Harbour National Park and parts of it are open for tour. The underground tunnels and the plotting room are the highlight, a complete World War II command infrastructure, intact, clean and thoroughly strange in the context of the harbour views from directly above. Number 13. The Callan Park Asylum, Roselle, Sydney. Located on the water's edge of the Parramatta River in the inner Sydney suburb of Roselle, Callan Park is one of the stranger pieces of real estate in the city. The 174 hectare site contains an elaborate complex of Victorian and Edwardian buildings arranged across grounds that slope gently down to the and most Sydneysiders who have driven past it on Victoria Road over the years have probably wondered at some point what the large stone buildings behind the fence were and why no one seemed to be doing anything with them. The site was established as the Hospital for the Insane, Callan Park in 1885 on land that had previously been a private estate and it operated as a most of which retained the word hospital. At various points it housed more than 2,000 patients. Much of what has been documented about its earlier operational period is grim in the way that pre-reform psychiatric history tends to be. Overcrowding, inadequate staffing, treatment practices that reflected the era's understanding of mental illness rather than what we would now consider therapeutic or humane. Patients died here in large numbers and many were buried on site. The institution was progressively wound down from the 1990s onward as psychiatric care moved toward community-based models. Today the site is managed by a combination of the NSW Government, the University of Sydney which uses some buildings for its arts faculty and the Sydney Harbour Federation Trust. Some buildings are accessible, many are not, as the grounds are open to the public as parkland. But the core of the historic complex, the large sandstone asylum buildings with their long wards and their enclosed courtyards and their institutional scale, sits in a peculiar administrative limbo, neither demolished nor fully repurposed. Their walls deteriorating behind chain-link fencing that cordons off sections from the public. The combination of visible architectural grandeur, documented institutional history and obvious state of managed neglect makes Callan Park one of the more quietly confronting places in the city. Number 12. The Morissette Asylum Ward, 21 Lake Macquarie. About two hours north of Sydney on the western shore of Lake Macquarie and the Morissette Hospital complex contains what remains of Ward 21. The section of the institution that was known by the even less formal designation, The Crim. Morissette Hospital was opened in 1909 as a psychiatric facility and operated as such for the better part of the 20th century. Ward 21 was the ward for criminally insane patients, a classification that at various points in the institution's history could encompass an extremely wide range of behaviours and circumstances. The ward closed in 1991 when a newer psychiatric facility was built elsewhere on the site. What remains of the closed wards is a collection of buildings in varying states of deterioration that are considered among the more photographed abandoned institutional sites in New South Wales. The combination of the Lake Macquarie location, the Victorian era architecture and the specific history of the criminally insane designation makes it a magnet for people who are interested in the history of Australian psychiatry and for urban explorers who find it somewhat less demanding of an access effort than some of the more remote sites in the state. Parts of the hospital grounds are accessible, the closed ward buildings are considered private property and entry to the building interiors is not permitted. Whether that consideration deters everyone who visits is a question that the comments sections of several urbex photography accounts have addressed with characteristic ambiguity. Number 11. The Quarantine Station, North Head, Sydney Harbour. The same headland that contains the North Head fortifications also contains one of the most historically significant and least visited heritage sites in Sydney. The North Head Quarantine Station, formally established in 1832 on the shores of Spring Cove inside Sydney Harbour National Park, was the point at which all incoming ships suspected of carrying infectious disease were intercepted and their passengers detained before being permitted to enter the city. For almost 150 years this station processed tens of thousands of people who had survived the voyage from Britain, Europe and Asia only to find themselves detained in Spring Cove for weeks or months while medical officers assessed whether they were carrying smallpox, cholera, typhoid or plague. Shared the conditions varied over time and by the class of the incoming passengers. First class passengers were accommodated in relative comfort, third class passengers were not. The station's medical history is a catalogue of epidemic management in an era before antibiotics when the principal tools of public health were isolation, fumigation and time. Close to 600 people died here and are buried in the on-site cemetery. The collection of buildings that remains, shower rooms, fumigation chambers, laundry buildings, dormitories, a church, the inspector's quarters, constitutes one of the most complete 19th century quarantine stations in existence. Today it operates as Kew Station Hotel and Conference Centre, running history and ghost tours through the heritage buildings. The ghost tour demographic should not require explanation. 10. Fort Scratchley, Newcastle The Newcastle coastline has its own coastal defence history and its most significant remnant is Fort Scratchley on the headland at the mouth of the Hunter River, a fortification that holds the distinction of being the only Australian fort to have engaged an enemy vessel in combat on Australian soil. On the 8th of June 1942, the Japanese submarine Y-21 surfaced off the Newcastle coast and fired approximately 34 shells at the city, the first hostile attack on an Australian urban centre since European settlement. Fort Scratchley returned fire, preventing the submarine from moving closer inshore and contributing to its eventual withdrawal. The exchange lasted approximately 90 minutes. The fort had been established in 1882 during a period of Russian scare that periodically gripped the colonial governments throughout the latter 19th century. By 1942 it had been upgraded with additional gun emplacements and a network of underground tunnels connecting various parts of the fortification. The guns that fired on Japanese submarines were eventually joined by more modern anti-aircraft batteries during the later years of the war. The fort was decommissioned after the war and spent several decades in various states of administrative limbo before eventually being opened to the public as a heritage site. Today the underground tunnels are accessible, the gun emplacements are preserved and the historical interpretation of the 1942 engagement is frank about the fact that the Japanese submarine's shells struck residential areas of Newcastle and caused damage to property and infrastructure, though no deaths resulted directly from the bombardment. Number 9. Hill 60, Port Kembla. Port Kembla is best known for the massive steelworks that dominate its shoreline, but the hill directly adjacent to the industrial site contains a network of concrete bunkers and tunnels that were built in the 1930s and 1940s as a coastal defense installation for the Illawarra region. The bunkers were constructed to protect the steelworks, which were considered a critical strategic asset during the Second World War from naval or aerial attack, and they provide a visual contrast that photographers find irresistible. Brutalist concrete defense infrastructure built into a promontory with the active industrial complex of the steelworks visible directly below and Wollongong Bay stretching out to the south. Hill 60's bunker system includes gun emplacements, observation posts and connecting tunnels that are open for public inspection as part of the heritage trail managed by the Port Kembla Community Forum. The site requires only a short walk from the roadside and provides views that encompass both the industrial present of Port Kembla and the defensive infrastructure of its wartime past. It is, by any measure, a genuinely unusual place. Military architecture built for purposes that fortunately were never fully tested, overlooking a steelworks that never stopped operating. Number 8. The Mittagong Ironworks Ruins, Southern Highlands. Before Mittagong became best known for its proximity to the Southern Highlands wine region, it had an earlier identity as the site of New South Wales' first ironworks. The Mittagong Ironworks were established in 1848, making them among the earliest attempts at industrial iron production in colonial Australia. The site was chosen because iron ore deposits had been found in the area and the local coal and timber resources seemed sufficient to fuel a smelting operation. The venture operated intermittently through the mid-19th century and the ruins of the original blast furnace and associated structures are still visible on the edge of the town, partially within what is now a reserve. The ironworks failed for reasons that were common to early colonial industrial ventures. The ore grades were inconsistent, the transportation costs to Sydney were high, and the management of the operation lacked the technical expertise to keep pace with the metallurgical developments happening in Britain and elsewhere. What remains is a section of the original stone blast furnace wall and associated foundations, heritage listed but not comprehensively maintained, tucked away in a corner of Mittagong that most visitors to the Southern Highlands never seek out. The irony of a region now celebrated for artisanal cheese and cold climate wine, having once produced iron, is not lost on the few people who know the history. Number seven, the Glen Davis Shale Oilworks, Kapiti Valley. This is the second of the two NSW shale oil sites and it is the more extensive and more accessible of the pair. Glen Davis is located about 70 kilometres north of Lithgow in the Kapiti Valley and the ruins of the shale oil processing plant that operated here from 1940 to 1952 constitute one of the largest collections of abandoned industrial infrastructure in the state. The site was established to produce petrol from oil shale for national defence purposes during the Second World War, using retorts transferred from the already defunct Nunes Operation in the Walgan Valley. At its peak, around 2,500 people lived in the township of Glen Davis. A planned company town built under an Act of NSW Parliament in December 1939 and designed according to town planning principles that were considered modern at the time. Or there was a hotel with 25 rooms, there were permanent brick houses, staff barracks accommodating 300 men, a school, an ambulance station with two ambulances funded by the residents themselves through subscription and a bakery. The water supply was piped 105 kilometres from the Oberon Dam, one of the few cases in NSW history of water from the Murray Darling catchment being supplied east of the Great Dividing Range. The works closed in 1952 when the post-war availability of cheap imported petroleum made the economics of domestic shale oil production untenable, and the population departed rapidly. Today, the ruins of the retorts, workshops, processing buildings, and power station remain on the valley floor, and surrounded by the vertical sandstone cliffs of the Capitea Scarpment and the vegetation of Wollemi National Park. Guided tours of the ruins run on Saturday afternoons and cost $25 per adult. The contrast between the industrial scale of the surviving structures and the extraordinary natural setting in which they sit is, by repeated visitor account, something that photographs do not fully capture. Number 6. The Murrelland Cement Works, Southern Tablelands. The Southern Tablelands town of Murrelland sits on the Hume Highway about 200 kilometres south of Sydney, and if you pull off the highway and take the road into town, you will encounter a large collection of ruined industrial buildings that were once one of the most important cement production facilities in NSW. The Murrelland Lime and Cement Works were established in the late 19th century to exploit the limestone deposits in the area, and the resulting industrial complex grew over the following decades into a significant employer for the region. At various points, it supplied cement for major infrastructure projects across NSW. The works were eventually wound down as the economics of the regional cement industry shifted, and more efficient production facilities elsewhere made the older Murrelland site uncompetitive. What remains is a collection of kilns, processing buildings, and assorted industrial infrastructure in varying states of collapse, on the edge of a town that has shrunk considerably from its industrial era peak but not entirely disappeared. The ruins are accessible from the and visible from the highway for anyone who knows to look. Most don't. When the Hume Highway was being upgraded and extended through the NSW Tablelands in the mid-20th century, a series of tunnels and cuttings were constructed to allow the road to pass through terrain that would otherwise have required extensive earthworks. Several of these tunnels were subsequently bypassed by later alignments of the highway, leaving them standing in the landscape. Complete road tunnels, lined in concrete or stone, accessible at both ends, going nowhere. The surrounding approaches have been closed off or incorporated into the scrub. The tunnels sit in the paddocks and bush of the southern Tablelands. Occasional diversions for people who know to look. The most interesting of these in the historical sense involves the road diversions made during the construction of the Snowy Hydro scheme in the 1950s and 60s, when entire sections of the Snowy Mountains Highway and associated routes were relocated to accommodate the engineering works. The structures left behind from this process, bridges, retaining walls, road cuttings, and in some places tunnels, constitute a distributed archaeology of one of the largest construction projects in Australian history, dispersed across a landscape that most people visit only for the ski fields or the Kosciuszko wilderness. Number 4. The North Head Quarantine Cemetery and Inscriptions, Sydney Harbour. What within the quarantine station precinct at North Head is a detail that no amount of hotel marketing fully prepares visitors for. The sandstone cliffs around Spring Cove are covered in inscriptions carved by the thousands of people who were detained there. Names, dates, ship names, countries of origin, messages in multiple languages, some deeply melancholy, some matter of fact, some recording the death of a family member during the detention, carved into the stretched across the rock face for hundreds of metres. The inscriptions were made by people who had no other way to mark their passage through the station, who had survived a voyage of many months only to find themselves detained indefinitely in a cove from which they could see the city they had come to reach. The Heritage Council of New South Wales has documented several thousand of these inscriptions. They are considered one of the most significant collections of migration era historical evidence in the country. The oldest date from the 1830s. There are inscriptions in English, German, Italian, Chinese and other languages. There are family names that appear repeatedly on adjacent panels of rock, suggesting that a family arrived together and each member carved their own record. There are single names with dates that correspond to the dates in the station's mortality register. The inscriptions are protected under heritage legislation and no new carvings are permitted, but they are also simply there on the cliff face, waiting to be read by anyone who takes the ferry to the quarantine station and walks along the rock platform at low tide. Number three, the Sydney Harbour Defensive Network, Multiple Headlands. Building on the individual fortification entries earlier in this list, it is worth stepping back to appreciate the full scale of what was constructed across Sydney Harbour's headlands during the Second World War, because taken together it represents one of the largest pieces of infrastructure in the city's history that almost nobody knows about. The Defensive Network ran for approximately 300 kilometres along the NSW coastline and included at its Sydney components alone, installations at North Head, South Head, George's Head, Bradley's Head, Bear Island and several other locations, all connected by a system of telephone lines. All underground plotting rooms, observation posts and physical fortifications. Bear Island Fort, connected to the Colonel Peninsula by a wooden footbridge, was the most southerly of the inner harbour defences and was built in 1885 during the same colonial era scare that produced Fort Scratchley in Newcastle. It was used again in both world wars, housing garrison troops and later serving as a prisoner of war camp. Today it is accessible via the La Perouse Historic Site and offers tours. George's Head in Mosman contains extensive tunnels and gun emplacements from both the First and Second World Wars, connected to the harbour foreshore by the road infrastructure of the Mosman Military Reservation. South Head in Watson's Bay contains the remains of a substantial military presence dating from the earliest colonial period through to the 1950s. Most Sydney-siders who visit these headlands for the views have no idea that the ground directly under their feet contains a complete military underground. Number 2. The Abercrombie Caves and Cast System, Central Tablelands. About 270km west of Sydney, in the Central Tablelands near the town of Trunky Creek, there is a cast cave system of considerable scale and geological age that most NSW residents have never visited and many have never heard of. The Abercrombie Caves are not secret in the way that some of the other entries on this list are secret. They are managed by the NSW Government, there are campgrounds, sure there are tour bookings and a heritage listing, but the combination of their size, their age and their architectural quality makes them worth including in any list of NSW places that exceed the expectations of people who make the journey. The main chamber of the cave system, known as the Grand Arch, is a natural limestone arch approximately 50m high, 35m wide and 50m deep, large enough to accommodate a substantial building inside it, which the Gold Rush era settlers of the Central Tablelands periodically used it for, holding dances and public meetings in the cave because it was the largest covered space available to them. The age of the formation is estimated at 340 million years. The cave system extends well beyond the main arch into a series of passages and chambers that vary in their accessibility. The whole system sits in a landscape of pastoral country and remnant box-iron bark forest that looks, from the highway, entirely ordinary. The final entry on this list is not a single place but a distributed network of structures, some entirely overlooked, that collectively represent one of the most significant inscriptions of human labour in the country's history, and that carry the unusual distinction of being jointly awarded World Heritage status in 2010 under the listing Australian Convict Sites. Eleven sites across New South Wales, the ACT, Tasmania and Western Australia were included in this listing, all of which the NSW components include Hyde Park Barracks in Sydney, now a museum, the Old Government House at Parramatta, also accessible, Cockatoo Island in Sydney Harbour, now a campground and arts venue, the Old Great North Road north of Sydney, partially accessible, the Brickenden and Woolmers Estates in Tasmania, the Cascades Female Factory, Tasmania and several others.