The Käfigturm is still called Bern's Prison Tower, though it hasn't been a dungeon since the late 1800s. It began around 1256 as a medieval city gate. After a fire, its replacement was built to hold about 65 prisoners. Today it houses the Polit Forum Bern, where political debate takes place.

The tower's fierce side survives in its bells. They date from 1643, when metal was scarce during the Thirty Years' War, and the story goes that the town bought a bell captured as war booty. The French-made bells carry an inscription: "May my voice be a terror to all the evil spirits." No one has come looking for them. The clock is just as stubborn. It runs for 36 hours at most, so someone cranks it by hand, hauling up weights of 45 and 85 kilograms.

VoiceMap's self-guided audio tour stops at the tower from both sides, then walks down Marktgasse to Bern's other famous clock tower, the Zytglogge.