Keystones from Portico of the Glory's Crypt

The crypt, also known as the "old cathedral," centers around a pillar with 8 engaged columns that support the arches of the ambulatory vaults. On the floor above, the Portico of Glory mullion sits on this great pillar in a layout that mirrors early French Gothic styles.

As well as being a structural part of the Portico of Glory, the crypt also forms part of its iconography, symbolizing the earthly realm that exists before Glory, represented on the floor above. Unlike the latter, the former, relies on celestial bodies for light, which explains why the keystones in the vaults of the central transept each feature angels carrying the sun and moon.