From Wikipedia: The church was destroyed during World War II, in the course of the Warsaw Uprising. During the aerial bombardment by German Luftwaffe in the first days of September 1944, the church was hit by 9 bombs resulting in collapse of the dome, main nave and one of the towers. In the years after the war it stood as a ruin while debates were conducted over whether to rebuild it to its pre-war appearance, or to its original appearance before reconstruction. In the end, the church was rebuilt between 1949 and 1952 in a form similar to its original design.