A part of the rampart walls built in 1386; the wall is still almost entirely intact. Four towers are open to the public: Schirmer, Zyt, Wacht and Männli.A part of the rampart walls built in 1386; the wall is still almost entirely intact. Four towers are open to the public: Schirmer, Zyt, Wacht and Männli. The oldest city clock, built by Hans Luter in 1535, is in the Zyt tower. This clock is allowed to chime every hour one minute before all the other city clocks.