Plötzensee is a small glacial lake in Berlin. It is situated in the former borough of Wedding, now a part of Mitte, adjacent to the public park Volkspark Rehberge. The name stems from Plötze, one name for the roach in German, as the lake formerly teemed with it. Plötzensee is part of a chain of lakes stretching from the northeast to the Spree valley, formed in the last ice age. Until 1443, the nunnery of St. Mary at Spandau had the rights to the lake, but these were eventually assumed by the Prussian treasury.