he St. Johannstor was built together with the consruction of the last outer fortification of the town in the 14th century. In order to protect the order of St. John, the gate had been erected quite far downstream. Thus, a small corner of the town originated there, which was hard to defend.

An adjacent gate in front of the original one was added to it in the 15th century, as it was the case with the other main gates. In 1850, the city wall had to be pulled down because of a law in favour of the expansion of the town.

Today, only small parts of the ancient fortification and three out of seven gates still exist.