The cathedral was built in the second half of the 12C. It stands on the main square, 1.5m below the present ground level. From the top of its square tower there is a remarkable view of the town and the surrounding tidal flats. The south portal is a rare example of Danish Romanesque sculpture. Note, particularly, its carved tympanum depicting the Descent from the Cross.
Inside, there is a wide nave flanked by aisles and surmounted by a dome. You can see medieval and modern frescoes as well as mosaics.