This church has layers of history literally visible in its architecture. Originally there was a 6th-century chapel on this site founded by the Archdeacon Orso, a local saint. Most of this structure was destroyed or hidden when an 11th-century church was erected over it. This church, in turn, was encrusted with Gothic, and later Baroque, features, resulting in a jigsaw puzzle of styles, that, surprisingly, manage to work together. The 11th-century features are almost untouched in the crypt, and if you go up the stairs on the left from the main church you can see the 11th-century frescoes (ask the sacristan, who let you in). These restored frescoes depict the life of Christ and the apostles. Although only the tops are visible, you can see the expressions on the faces of the disciples. Take the outside doorway to the right of the main entrance to see the church's crowning glory, its 12th-century cloister, enclosed by some 40 stone columns with masterfully carved capitals depicting scenes from the Old and New Testaments and the life of Saint Orso. The turrets and spires of Aosta peek out above.