The cathedral of Vaison was built on the ruins of a Roman temple, the remains of which can be seen outside the chevet. More than one church has existed on this site; a 6th-century basilica was destroyed by Frankish invaders.
The present building dates primarily from the 11th and 12th centuries. After a dispute with the Count of Toulouse in the late 12th century, the medieval city of Vaison was mostly abandoned for the new town. Today, little remains of the extensive medieval city except for the cathedral.
The apse is the most interesting aspect of the interior. Behind a simple stone altar, on a lower level than the nave, is the medieval bishop's throne and three semicircular benches for the canons. In front of the throne is an old sarcophagus containing the relics of St. Quenin (d. 578). The apse also contains several tomb niches of various styles and some reliquaries and statues.
The cloister, dating primarily from the mid-12th century, is a peaceful space with a lush central garden. The canons' buildings, such as the refectory and dormitory, have disappeared and many of the capitals were restored in the 19th century, but the cloister retains its medieval appearance and atmosphere. Most of the capitals are carved with foliage and vines, but some have charming creatures and human faces.
Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.