The Nassau circular wall originally consisted of five towers. Today, two towers are still preserved: the Eimelsturm at the Nassau cemetery and the Graue Turm in Grabenstraße.
The Eimelsturm is part of the former "Emser Tor", which was never demolished in 1787 due to dilapidation. On the ground floor there is a memorial hall for the victims of the two world wars and the Nazi regime.