The only tower to be decked out like a house, this 37m-high pentagonal stone tower has leaned slightly to one side ever since building was complete in 1376. It was originally used for both defensive purposes and as a royal residence, and the different rooms can still be visited. City views from the rooftop terrace are predictably fine – count 120-odd steps in total to the top.
Consider renting an audioguide (€3) to get the most out your visit. In season free guided tours depart at 11am and 3pm.