Fodor's Expert Review Oppenheimer Kellerlabyrinth

Beneath Oppenheim's surface, there are five layers of cellars, tunnels, and stairways. Thought to have been built in the 14th century, their purpose remains unknown. Of the 40 km (24 miles) of complex underground passageways, today ¾ km (½ mile) is open to the public; contact the Oppenheim tourist office to arrange a tour.