Founded in 1027, the cathedral of Susa, in Latin cross format with three naves and a transept, rises with the facade wall set on the Roman and medieval walls, incorporating in the left corner one of the Roman towers of the gateway called "Savoia" or "del Paradiso". By the left aisle there can still be clearly seen a part of the Roman structure in a cavity in the facade wall. The three naves are separated by irregularly shaped pillars with an obvious derivation from a primitive T shape which, in the first two, could also be cross-shaped. Longitudinal arches are set on the pillars along the entire curve without capital. Towards the central nave, around the pillars are thin columns with a cubic capital which support the lintels of the longitudinal arches.