There are the ramparts build by the Popes in the 14th century still entirely encircling the old town, kept and restored through the ages because in modern times still useful as barrier against the floods from the Rhône.
There is the cathedral, Notre Dame des Doms with its amazing blend of Baroque and Romanesque architecture inside, the splendid view from its doorsteps’ esplanade and the beautiful public gardens of the Rocher des Doms some 30 meters above the river dominating the city and surrounding countryside with the famous Mont Ventoux in the distance.
And, “bien sûr”, there is the Pont d'Avignon, the broken bridge, only four arches left of twenty-two, build in 1234 and destroyed by a catastrophic flood in 1669. It is this bridge that the famous song “Sur le pont d’Avignon, on y danse, on y danse”. You can watch here a 3-D reconstruction: