West (1.5km/1 mile) of the town center, the ruins of the nearly 1,000-year-old Hamar Cathedral jut out into Lake Mjøsa. The sight can be reached by a scenic walk, or you can take bus no. 6 leaving from the Hamar Library, costing NOK60 ($12/£6) one-way. These ruins are evocative and call attention to Hamar's once-important role in Norway's ecclesiastical world. The church was constructed of locally quarried limestone, with Romanesque architecture, although later additions were Gothic.

The ruins are protected by a steel-and-glass cover provided in 1998. This protective umbrella is the largest glass construction in Europe, fanning out for 2,600m (8,528 ft.). Adjoining is an archaeological museum displaying artifacts found in the area, and also an open-air folk museum featuring 18th- and 19th-century houses. In an organic garden you can see nearly 400 different types of herbs. The best time to visit these ruins is in summer when concerts or plays are also presented.