The Zoo flak tower was a fortified flak tower that existed in Berlin from 1941 to 1947. It was one of several flak towers that protected Berlin from Allied bomber raids. Its primary role was as a gun platform to protect the government building district of Berlin; in addition, the Hochbunker (blockhouse) was designed to be used as a civilian air-raid shelter. It also contained a hospital and a radio transmitter for use by the German leadership and provided secure storage facilities for art treasures.