Complex sentence: The ruins of both the old and new Chancellery buildings were levelled by the Soviets between 1945 and 1949 to destroy the landmarks of Nazi Germany but the bunker largely survived, although some areas were partially flooded.
Split into simpler sentences: The ruins of both Chancellery buildings were levelled by the Soviets between 1945 and 1949 to destroy the landmarks of Nazi Germany. But the bunker largely survived, although some areas were partially flooded.