5 Best Sights in Piedmont and Valle d'Aosta, Italy

At the eastern entrance to town, and commanding a fine view over Aosta and the mountains, stands the Arco di Augusto (Arch of Augustus), built in 25 BC to mark Rome's victory over the Celtic Salassi tribe. (The sloping roof was added in 1716 in an attempt to keep rain from seeping between the stones.)

Aosta's cathedral dates from the 10th century, but all that remains from that period are the bell towers. The decoration inside is primarily Gothic, but the main attraction of the cathedral predates that era by 1,000 years: among the many ornate objects housed in the treasury museum is a carved ivory diptych from AD 406 portraying the Roman emperor Honorius. You can also see frescoes dating from the 11th century above the Gothic vaults. The treasury and frescoes can only be visited on weekends between 3 and 5:30 pm, or with advance reservation on weekdays (except Wednesdays) also from 3 to 5:30 pm.

Originally there was a 6th-century chapel on this site, founded by the Archdeacon Orso, a local saint. Most of the structure was destroyed or hidden when an 11th-century church was erected over it. If you go up the stairs on the left from the main church you can see the frescoes of Christ and the apostles (ask the sacristan, who'll let you in). Take the outside doorway to see the church's crowning glory, its 12th-century cloister, enclosed by some 40 stone columns with carved capitals depicting scenes from the life of St. Orso.

This huge gateway, regally guarding the city, is a remarkable relic from the Roman era. The area between the massive inner and outer walls was used as a small parade ground for the changing of the guard.

The 72-foot-high ruin of the facade of the Teatro Romano guards the remains of the 1st-century-BC amphitheater, which once held 20,000 spectators. Only a bit of the outside wall and seven of the amphitheater's original 60 arches remain. The latter, once incorporated into medieval buildings, are being brought to light by ongoing archaeological excavations.