Kilkenny is compact enough to walk end-to-end in about 20 minutes, which makes it one of the most agreeable cities in Ireland to explore on foot. The medieval mile between the castle and St Canice's Cathedral is the main axis — along it you'll find the castle gardens, the Tholsel (the old city hall), and a cluster of well-preserved Norman buildings.
The Medieval Mile Museum runs free walking tours in summer that cover the main sights, but you can easily navigate without a guide. Pick up a map at the tourist office on Rose Inn Street and follow the coloured markers on the pavement.