Bremen Cathedral (), dedicated to St. Peter, is a church situated in the market square in the center of Bremen. The cathedral belongs to the Bremian Evangelical Church, a member of the Protestant umbrella organization named Evangelical Church in Germany. It is the previous cathedral of the former Prince-Archbishopric of Bremen. Since 1973, it is protected by the monument protection act. Periods and materials In general, Bremen Cathedral is a medieval building. The oldest visible structures are the two crypts. The last parts built in romanesque style and in sandstone were the lower storeys of the western façade and the western towers. Since the late 1220s, vaults and walls were erected in bricks, partly hidden by sheets of sandstone. Only the outer wall of the southern row of chapels shows unhidden bricks. St Peter's is one of the largest historic brick structures in Europe, but it comprises too many stone structures to be subsumed to Brick Gothic. During the great restoration of 1888 to 1901, the western towers and most of the western façade were rebuilt relatively close to previous structures. The crossing tower was a new addition, using the medieval crossing tower of Worms Cathedral as an example. The roofs above the transepts and the northern aisle were redesigned. History Early buildings The first church structure that can be verified on the site of St Peter's Cathedral in Bremen was a timber church on a high point overseeing the Weser River built by Saint Willehad, an early missionary to the Frisians. The church was built about 789 in conjunction with the creation of the Diocese of Bremen, with Willehad as the first bishop. Willehad died the same year. Just three years later Saxons attacked and burned Bremen and its tiny timber cathedral. No trace of it remains. The see remained vacant for thirteen years until it was reestablished under Bishop Willerich in 805. St Peter's was built as the cathedral church of local sandstone in several stages by Bishop Willerich. After the sack of Hamburg by the Danes in 845, Bremen became the seat of the combined Bremen and Hamburg Archdiocese under Archbishop Saint Ansgar who held the see from 848 to his death in 865. He was one of the most prominent missionaries to northern Europe and is credited with the beginnings of the conversion of the Danes and Swedes to Christianity. He was succeeded by Archbishop Rimbert.