The Collegiate church of Sant'Orso stands just east of the Porta Praetoria, outside the Roman walls, at the point where a pre-Roman sanctuary once stood. The church is dedicated to Saint Ursus of Aosta, an early Christian missionary, and the site has been a place of worship since at least the 6th century. The current buildings are largely 11th and 12th century, with later additions and restorations, but the core of the complex retains its Romanesque character.
The cloister is the highlight: a double colonnade enclosing a small garden, with 54 carved stone capitals on the columns. The carving — thought to date from around 1133 — covers an extraordinary range of subjects, from formal biblical scenes to acrobats, monsters, and ambiguous figures that have fascinated art historians for generations. The choir stalls inside the church are equally notable: 98 carved wooden seats dating from 1469, with misericords (the small ledges on the undersides of the hinged seats, carved to support standing monks during long services) that include some of the most inventive woodcarving in the Alpine region. The church also holds a Romanesque bell tower, frescoes in the crypt, and a small treasury. Entry to the cloister is free; the treasury has a separate admission.