The town wall, which was built in the early 13th century and some of whose parts are open to the public, was expanded and strengthened in the 14th century, and with 16 defensive towers – among them the "Hospitalgassenturm" (“Hospital Lane Tower”), the "Steingassenturm" (“Stone Lane Tower”), the "Katzenturm" (“Cats’ Tower”) and the "Ochsenturm" (“Ox’s Tower”), which is crenellated and has an octagonal top tower, making it a type of butter-churn tower ("Butterfassturm") – is the best preserved girding wall anywhere on the Rhine Gorge. There was planning to open further sections to the public in 2006.