In 1910, explorers Knud Rasmussen and Peter Freuchen established an outpost on the northwest coast of Greenland. They called it Thule ("Toolee"). The name is from the "Ultima Thule" of ancient geographers, referring to the farthest north land known to be inhabited by humans.

In the early 1900s, the Inuit knew Thule as a trade, medical and social center. Today it is the U.S. Armed Forces' northernmost base which includes a Space Warning Squadron and a Ballistic Missile Early Warning Site designed to detect and track missiles launched against North America.

When the base was planned, it was not known what the coldest Arctic temperatures or strongest winds might be, so everything was built to withstand temperatures as cold as -100F / -73C and winds of up to 200 mph / 320 km per hour.

Thule sits on 1600 feet / 490 meters of permafrost, and as long as everything stays frozen, the buildings sit on solid ground. Ground level buildings have double floors with cold air circulating between them, and other buildings are well above ground to prevent the permafrost from thawing out. If it did, the buildings would be sitting on a slushy mix of water and gravel.

What doesn't Thule have? A view of the Northern Lights! The base is almost directly in the center of the "auroral oval" and is too far north to see them.