During the siege of Leningrad (1941–1944), the Observatory became the target of fierce German air raids and artillery bombardment. All of the buildings were completely destroyed. Under dramatic circumstances, the main instruments were saved and stored safely in Leningrad, including the lens of the destroyed 30-inch refractor, and a significant part of the unique library with manuscripts and important works from the 15th to 19th century. On February 5, 1997, nearly 1,500 of the 3,852 books were destroyed by malicious arson and the rest of the library items were damaged by flames, smoke or water.