Markus's tower is part of the remains of the first city wall built in 1172. The original wall was mostly destroyed or allowed to fall into ruin in the 14-th century, when a second external city wall was built to surround the growing city. A remnant of the original walls and towers can be found along Rödergasse between the Röder Gate and the Markt, where the Markusturm (Markus Tower) and Röder Arch were built in the early 13th century. (By the way, the building just south of the tower is the Romantic Hotel Markusturm. It is a lovely place where I stood during my two days there.