The Mangturm (Mang Tower) - located on the harbour promenade - is a square stone building, which was constructed in the 12th century as part of the medieval city fortifications. The tower had a height of 35 metres high and was equipped with embrasures. The Mangturm was a perfect observation post at the end of the city wall, which also included two neighbouring towers. In order to send signals to ships on Lake Constance, fire baskets were hung on a pole outside the tower.

After the construction of a new lighthouse in 1856, the Mangturm lost its function as a watchtower and signal tower. It was raised by one storey and covered with the distinctive glazed tiles. In 1914, the former tower keeper’s apartment on the upper floor was converted into a viewing room.