The Diocese of Ratzeburg (German: Bistum Ratzeburg, Latin: Dioecesis Ratzeburgensis) is a former diocese of the Catholic Church. It was erected from the Diocese of Oldenburg c. 1050 and was suppressed in 1554. The diocese was originally a suffragan of the Archdiocese of Hamburg; in 1072 it became a suffragan of the merged entity — the "Archdiocese of Hamburg and the Diocese of Bremen". The territory of the diocese was located in what is today the states of Schleswig-Holstein (the district of Herzogtum Lauenburg) and Mecklenburg-Vorpommern (the district of Nordwestmecklenburg) in Germany. The cathedral church of the diocese — dedicated to Ss. Mary and John — is still extant in the city of Ratzeburg. Following its suppression as part of the Protestant Reformation, the remaining Catholic adhe