Guarded by hulking fortifications, this massive edifice was home to Trento's bishop-princes until Napoleon's arrival in 1801. Enclosed within is the original 13th-century castle, the Castelvecchio, along with the residential rooms of the Renaissance-era Magno Palazzo, and the upstairs loggia with its lovely Adige valley views. Pay separate admission to visit the Torre Aquila, the castle's showpiece tower, adorned with a 14th-century 'months of the year' fresco cycle depicting May garden parties, the October wine harvest and a medieval snowball fight.