Chur Cathedral, otherwise the Cathedral of the Assumption of Mary (German: Kathedrale St. Mariä Himmelfahrt), is the Catholic cathedral of the diocese of Chur. The episcopal palace of the bishop of Chur is beside the church. The cathedral claims the relics of St Lucius of Britain, said to have been martyred nearby in the late 2nd century. During the Swiss Reformation, the Catholic population of the city were confined to a ghetto enclosed around the bishop's court beside the cathedral. It is a Swiss heritage site of national significance.The first building on the site probably dates from the first half of the 5th century.The second church was built by Bishop Tello at some time before his death in 773. The current building was built between 1154 and 1270. In 1272 it was dedicated to the Assumption of the Blessed Virgin Mary. The round arch window along the center axis is the largest medieval window in Graubünden. The late-Gothic high altar was completed in 1492 by Jakob Russ.