A thermal drill at Camp CenturyProject Iceworm (America's Secret Tunnels Beneath Greenland's Ice), was one of the strangest military projects to come out of the Cold War.
https://www.atomicheritage.org/history/camp-century
A City Under the Ice
'Construction on Camp Century began in June 1959 and was completed by October 1960. Army engineers first had to build a three mile road to bring the 6,000 tons of supplies it would require to build the $8 million facility. Most of the heavy equipment, including vehicles, were brought by bobsleds known as “heavy swings” which had a maximum speed of two miles per hour, making it a 70 hour trip from the Thule Air Base.'
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Project Iceworm
The scientific developments at Camp Century were a cover for the U.S. Army’s true operation, codenamed “Iceworm,” which sought to deploy ballistic missiles under the Greenland ice. Although the project was eventually canceled and no missiles were ever deployed to Greenland, it would have been an extraordinary engineering and construction achievement had Iceworm come to fruition.
Legacy (concern over Project Iceworm’s technical feasibility was the primary factor in its demise.)
..."The U.S. Army continued to operate Camp Century in a limited capacity until 1966. Its tunnels quickly collapsed, and today the facility is unreachable, buried under a thick layer of ice. Project Iceworm remained a closely guarded secret until 1997, when the Danish Institute of International Affairs (DUPI) reported Camp Century’s military ambitions.
In recent years, climate change scientists have warned of severe consequences should the Greenland ice sheet melt enough to reveal Camp Century. During its operation, the facility’s nuclear reactor produced over 47,000 gallons of radioactive waste. Although the reactor was removed, this waste remains buried under the ice to this day
https://www.atomicheritage.org/history/camp-century
(Includes an old video promoting the camp and showing footage of how it was built).
See more here:
https://www.damninteresting.com/the-city-under-ice/