Walls of Light

When Abbot Suger renovated the Basilica of Saint-Denis near Paris around 1140, he replaced solid stone walls with enormous stained glass windows. Colored light flooded the interior, and Suger declared it a preview of heaven. This architectural revolution launched the Gothic style that would dominate European building for three centuries.

The engineering breakthrough was the pointed arch, which distributed weight more efficiently than the rounded Roman arch. Combined with flying buttresses and ribbed vaults, it allowed builders to dissolve walls into glass, flooding interiors with light.