Bregenz in the summer lends itself to bicycle tours, swimming, sailing or sightseeing, whereas, during the winter season, visitors populate the numerous slopes and hiking trails of the Vorarlberg. The town is noted for its Upper City with the St Martinstrum (St Martin’s Tower), the world’s largest floating stage for summer opera productions, the Congress Center, the Mehrerau Abbey Church, the Vorarlberger Landesmuseum with its superb 16th-century paintings and works by late 18th-century artist Angelika Kauffmann. A cable car runs to the viewing platform on Mount Pfänder where one can watch the flight of birds of prey as well as scenic views over Lake Constance.