What brought down Beauvais, the tallest Gothic choir ever built?

Two collapses, three centuries apart, and a building that has needed propping ever since. In 1284, part of the vaulting of the recently completed choir fell. In the race to build the tallest cathedral of the 13th century, the buttresses had been made thinner to let in a maximum amount of light, and it is now believed that the collapse was caused by resonant vibrations due to high winds, a modern reading rather than a medieval verdict. The builders did not give up on height: the choir was rebuilt at the same height, with more columns, changing the vaulting from quadripartite to sexpartite.

The second fall came from a fresh ambition. A 153-metre tower was finished in 1569, making the church the tallest structure in the world at the time. On Ascension day in 1573 the tower and crossing vaults collapsed. Work on the nave began in 1600, but only its first arch was built before construction was halted for the final time.

The modern chapter shows how delicate the balance still is. Iron supports were added between the flying buttresses in the 18th century. When these tie rods were removed in the 1960s as unnecessary, the wind oscillations were amplified and the choir partially separated from the transept. The rods went back in steel, which is less ductile than iron, so the structure became more rigid, possibly causing additional fissures. In the 1990s large wood-and-steel trusses and a 45-degree brace were installed to keep the north transept from collapsing, and in September 2022 a restoration began, starting with the roof and the removal of the interior supports.