Chapel Bridge and Water Tower ("Wasserturm") mark the upper end of the medieval bridgehead city of Lucerne where the waters of Lake Lucerne flow intoRiver Reuss. Originally the Chapel Bridge and Water Tower were parts of the oldest medieval city ramparts of Lucerne. The northern bridgehead of Chapel Bridge once lead directly into St. Peter's Chapel. Today,a riverside promenade separates the two. This octagonal tower - over 34 meters high (111.5 ft.) - was built around 1300 as part of the city wall and used as an archive, treasury, prison and torture chamber. It is Lucerne's landmark and the most frequently photographed monument in Switzerland.