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.
The trulli, typical limestone dwellings of Alberobello in the southern Italian region of Puglia, are remarkable examples of corbelled dry-stone construction, a prehistoric building technique still in use in this region. These structures, dating from as early as the mid-14th century, characteristically feature pyramidal, domed, or conical roofs built up of corbelled limestone slabs. Although rural trulli can be found all along the Itria Valley, their highest concentration and best preserved examples of this architectural form are in the town of Alberobello, where there are over 1500 structures in the quarters of Rione Monti and Aja Piccola.
The property comprises six land parcels extending over an area of 11 hectares. The land parcels comprise two districts of the city (quarters or Rione Monti with 1,030 trulli; Rione Aia Piccola with 590 trulli) and four specific locations.
Trulli (singular, trullo) are traditional dry stone huts with a corbelled roof.