Arising in northern France around 1140 and spreading across Europe by 1500, the Gothic cathedral solved a structural problem and turned the solution into theology. Pointed arches, ribbed vaults, and flying buttresses transferred the roof's weight onto an external skeleton of stone, freeing the walls to be dissolved into stained glass. The interior of Chartres or Amiens soars far overhead and glows from every side. These buildings were the work of generations — often a century or more — funded by church, towns, guilds, and pilgrims, and many were never finished as planned.
A medieval mason could not lift the roof of a stone church much higher without the walls buckling under its weight. The Gothic builders solved that problem and turned the solution into a machine for making heaven visible. They carried the load on a skeleton of pointed arches and ribbed vaults, then propped the outside with arms of stone called flying buttresses. The walls no longer had to hold anything up. So they cut them away and filled the gaps with colored glass. Inside, a building like Chartres or Amiens soars far overhead and glows from every side, as if engineering itself had been bent into an argument for God.