The original town wall was successively reinforced in the 13th century and 36 defensive towers were added. The Kattenturm, whose construction dates back to 1230, is the last completely preserved of these fortifications. The defensive system was historically exposed to attacks from catapults, crossbows, storm ladders and so-called katten. Katten referred to concealed positional carriages that offered attackers protection when approaching the walls and gates. Another hypothesis for the origin of the name refers to a type of light cannon or the Low German verb "katten", which describes pulling upwards. The tower has six internal storeys, which were accessible by ladders. Its current proportion to the Wallmauer results from the lowering of the wall in the 19th century to make it a promenade, while the Kattenturm retained its original height.