The Basilica of Saint-Denis is where Gothic architecture was invented. Go round behind the altar and the chapels open into one another with no dividing walls, so coloured light reaches you from every side at once. Abbot Suger rebuilt the east end of his abbey church in the 1140s and put three things together that had existed separately: the pointed arch, the ribbed vault and the buttress outside the wall. Between them these three carried the roof, so the walls no longer had to, and he filled the space with coloured glass.
It is also the graveyard of the French monarchy. Kings and queens were buried here for twelve centuries, and about seventy carved figures lie on their tombs, from stiff twelfth-century slabs to Renaissance couples shown naked and dead. In 1793 the Convention had the tombs opened and the bodies thrown into two lime pits outside; the monuments survived because a scholar carted them away and put them on show as works of art. The bones were recovered in 1817 and returned to the crypt, all mixed together. The north spire, taken down in the 1840s, is being rebuilt by hand in a stoneyard beside the church.