Les Halles which contained row upon row of delicious foods of all kinds (not to mention it was air conditioned; not a minor attribute on such hot days).
Palais des Papes, which was quite interesting, although I kept getting told off for trying to take photos and it is anyway such a huge building it is a little overwhelming to try and take in (you can only listen to so many audio commentaries before fatigue sets in).
Pont d'Avignon. More audio guides. Actually, it was interesting to find out more about the history of the bridge and the associated song. Finally we walked up to the park above the Palais des Papes for a picnic and to see the view from above Avignon.
All my photos from Avignon are here.