Several massive air raids were directed at Helsinki during the Winter and Continuation Wars. Thanks to successful anti-aircraft defence, the raids caused relatively minor damage although human and material loss could not be totally avoided. T he heavy anti-aircraft unit `Taivas' (Sky) operated successfully on Käpylä's Taivaskallio hill in 1939. In its memory, the Helsinki air defence regiment's guild placed an anti-aircraft cannon on Taivaskallio. The memorial was unveiled on May 29, 1983.
