Favorite thing: visit the pinnacled Barbakan, the mid-16th century stronghold in the old city wall, now marks the boundary between the Old Town and the New Town (actually, both are very old). New Town was founded at the turn of the 14th and 15th centuries.
2001: Some fun guys at the wall around Old Town.. available with axe... for the crazy tourists with busy cameras.
The area around the Barbicon usually has some entertainers offering a variety of song and musical instruments. My trip in 2006 included more of this. An interesting couple sang old folk music to the crowds that gathered.
Favorite thing: It was constructed in 1548 to became a part of 1200 metres long city defence wall system. Nowadays it became a friendly place for painters and musicians.