North Warning System is Donovan Wylie's third and final book of photographs on the themes of vision and power in military architecture, and draws a close to his Tower Series. Surveying a radar station just inside the Canadian Arctic, Wylie examines the detection of invisible threats through unmanned observation posts in remote regions. The development of long-range bombers and missiles after the Second World War made Canada's arctic frontier vulnerable to attack from the air. This forced Canada and the United States to jointly construct a matrix of short and long-range radar...