U.S. Air Force personnel gather outside the Base Operations building at Thule Air Base, Greenland, in the early 1950s. Billed on its own signage as "The Northernmost Air Base In The World," Thule served as a critical Cold War outpost for strategic bomber staging and early-warning radar coverage against the Soviet Union, with structures elevated above the permafrost to withstand the extreme Arctic environment. Project: 218295