Building designed to sink slowly into the Greenland polar icecap, built by the Army engineers for the U.S. Air Force, are the first that have been built for continuous use on Thule Air Base. The vertical entrance towers are increased in height as the buildings sink lower into ice pack. The buildings are designed on an even keel, and sink at the rate of several feet a year. May 22, 1955. (Photo by Associated Press Photo).