Was Viollet-le-Duc restoring Notre-Dame or inventing it?

Both, and that is the point of the argument. Eugène Viollet-le-Duc was famous for restoring the most prominent medieval landmarks in France, but his own definition of restoration is not about copying: to restore a building, he wrote, is not to maintain, repair or remake it, but to re-establish it in a complete state which may never have existed at any given moment.

His rules were demanding in some ways and flexible in others. The re-establishment had to be scientifically documented with plans, photographs and archaeological records, to guarantee exactness. But the structure could be adapted to more modern or rational uses, even with alterations to the original plan. Critics accused him of pursuing the spirit of the Gothic style rather than strict historical accuracy.

Notre-Dame's spire is the perfect example. The medieval spire was removed in 1786 after wind damage, and Viollet-le-Duc designed a new one that was taller than the original and modified to resist the weather. His defenders point out that Prosper Mérimée and the Commission of historic monuments approved all his plans, and a panel near the altar of the cathedral says the nineteenth-century work is now as much a part of the cathedral's architectural history as that of previous centuries.

In 2019 the argument returned. After the fire destroyed the spire, a poll found 55% of French respondents wanted a flèche identical to the original, and in the end the new flèche was put in place on 16 December 2023, built by a team that scrutinised Viollet-le-Duc's own journal of his 19th-century work.