Passing the outer ward we reach the tower Bürgerkorpsturm, once called Heimatbundturm. This semicircular tower is about 13.5 metres high with a wall thickness of 2.7 m at the base and 1.2 metres at the top. This section of the city moat has a depth of 4.2 metres. It is presumed that the tower was once open at the back and that all four storeys could be used for defence. In addition there was a connection to the wall-walk. The embrasures of this tower are directed towards the outer ward and the city moat. Nowadays the tower is walled up at the back and hosts the citizens guard/the citizens corps, hence its name. Wooden water pipes, found in the city moat in 1988, are shown in the outer ward.