Consecrated in 1096, this is the largest and finest Romanesque church in Europe. One of its most outstanding features is the Porte Miègeville, opening onto the south aisle and decorated with 12th-century sculptures. The door into the south transept is the Porte des Comtes; its capitals depict the story of Lazarus. Nearby are the tombs of the comtes de Toulouse. Entering by the main west door, you can see the double side aisles that give the church five naves, an unusual feature in Romanesque architecture. An upper cloister forms a passageway around the interior. Look for the Romanesque capitals surmounting the columns.

In the axis of the basilica, in the ambulatory, 11th-century bas-reliefs depict Christ in His Majesty. The ambulatory leads to the crypt (ask the custodian for permission to enter), which contains the relics of 128 saints, plus a thorn said to be from the Crown of Thorns. The old baroque retables (altarpieces) and shrine in the ambulatory have been reset; the relics here are those of the apostles and the first bishops of Toulouse.