The Prison Tower is the mainstay of the second line of Bern`s fortified walls. If you go from the Main Train station to the Old Town, this will be the first tower on the main street. It is built of tuff and sandstone.
Bern is located in a deep bend of the river Aare and is surrounded on three sides by the riverbed. After the Foundation in 1191, the first defensive wall was built on the Eastern side. It was in place where now Zitglogge clock tower is located. 50 years later, in 1256, a second line of town fortifications was built in 300 meters to the west of the Zitglogge tower. The main Tower of second fortified wall line was Prison tower. But initially the tower was not a prison, but a defensive one.
In 1345, a third line of fortifications was built. It passed approximately where the Main station is now located. In 1405, there was a "Great fire" in the town, but the Tower of the second line of fortifications had strong walls and was not very damaged. The town authorities decided that it was suitable for its use as a town prison. Therefore, from 1405 to 1897, the tower officially became a Prison, and dozens of prisoners were held there.
In 1640, the old prison tower was demolished due to dilapidation, and in its place was built the Prison Tower of Bern, which we see today. Its height was 49 meters. In front of the tower was built square Barenplatz. It was also used as a fire alarm tower. A watchman watched the town, and in a room attached to it, a trumpeter was on duty, who in the event of a fire notified the town. In 1690, a clock with an artistic bas-relief "The Greatness of Bern" was installed on the tower.