Restoring Notre Dame’s Iconic Stained Glass

Inside Notre Dame, the first chance to get up close to the gigantic south rose window in 160 years has revealed a mystery. We only have 13th century glass and 19th century glass. In the 19th century they removed everything that wasn't 13th century and then they had to do new panels if a panel was missing. The chief suspect for these radical changes to the window is architect Eugène Viollet-le-Duc. In the 1840s he was tasked with breathing new life into Notre Dame. At the time it was not the beloved building we know today. The cathedral was ransacked during the French Revolution. Statues of biblical kings on the facade were decapitated and it was used as a warehouse, sitting derelict and unloved for decades. During his restoration, Le-Duc removed all glass in the south rose window that was not original and replaced it with modern glass. Elizabeth is also finding that he made significant alterations to some of the original glass panels. Why did Le-Duc alter the window? The glass experts hunt for clues here at the Paris Mediatheque of Architecture and Heritage. They hope Le-Duc's plans for the south rose window shed light on his thinking. As they dig into the archives, they make a breakthrough. We just discovered that there was a change of structure. Before Viollet-le-Duc there was an iron reinforcement in the center of the rose but obviously it wasn't enough so Viollet-le-Duc put it further away from the center and when you removed the ironwork here it had to change the form of the panels. Le-Duc's restoration was sweeping. He removed a smaller structural ring of iron and replaced it with a bigger ring to strengthen the core of the window. He removed all traces of previous restorations to replace them with panels of new glass and he rotated the whole window 15 degrees to make it structurally stronger. The problem must have been that the medieval rose wasn't stable in its axis. That must have been the problem. Le-Duc's major changes to the south rose were motivated by more than mere aesthetics. Strengthening the window has helped preserve this masterpiece.