The Marienkirche is a church in Frankfurt (Oder) in Germany. It was formerly the city's main parish church and was built over more than 250 years during the Middle Ages.
It was first built in 1253, just after the foundation of the city, and was one of the earliest examples of a gallery in the architecture of the Margraviate of Brandenburg. An ambulatory hall was built to replace the original choir and a polygonal entrance hall with a sandstone entrance arch built onto the north transept, both between 1360 and 1370. The nave was expanded as a five-bayed construction in the 15th century with painted ceilings in the side bays and a 14-storey new tower façade built around 1450. An eight-pointed cupola was added to the north tower and a crenellated edge to the south tower. On the establishment of the Viadrina University a new galleried sacristy was built between 1521 and 1522 - this was the last major expansion of the building, which is now 77 metres long and 25 metres wide, making it one of the largest Brick Gothic buildings in Germany.
The three large surviving Gothic stained glass windows date to between 1360 and 1370 - they are made up of a total of 117 pictures, each 83 x 43 cm in size, financed by city's citizens of the city and showing the creation, the lives of Adam and Eve, Noah building his ark, Christ's life and the Book of Revelation. They were removed to another location in Frankfurt in September 1941 to protect them from bombing - there they were photographed in black and white before being moved to the New Palace in Potsdam in April 1945.
In June 1946 they were seized from Potsdam by the Soviet Military Administration in Germany and taken to the Red Army Spoils of War Camp 1 at Zentralvieh- und Schlachthof in Berlin. They were then moved to the Hermitage Museum's stores in August 1946 and were thus considered as "lost since the end of the war". The windows' new location was first revealed in April 1991 by the Literaturnaya Gazeta. In 1994 Frankfurt's parish council petitioned the Russian prime minister Viktor Chernomyrdin for their return, leading to a law passed in the State Duma with the approval of the Federation Council in April 2002 to return the windows. They were gradually restored in a room above the church's sacristy from summer 2002 onwards, using the black and white wartime photographs.