UNESCO says:
In the 14th century, this city in the South of France was the seat of the papacy. The Palais des Papes, an austere-looking fortress lavishly decorated by Simone Martini and Matteo Giovanetti, dominates the city, the surrounding ramparts and the remains of a 12th-century bridge over the Rhone. Beneath this outstanding example of Gothic architecture, the Petit Palais and the Romanesque Cathedral of Notre-Dame-des-Doms complete an exceptional group of monuments that testify to the leading role played by Avignon in 14th-century Christian Europe.
Copyright © 1992 - 2006 UNESCO/World Heritage Centre. All rights reserved.

UNESCO world heritage site

chill888 says:
This deserves 5 stars. Amazingly well preserved medieval city. Stunning.