Camp Century is an abandoned Arctic United States military scientific research base in Greenland, situated 205 km (127 mi) east-northeast of Pituffik Space Base. When built, Camp Century was publicized as a demonstration for affordable ice-cap military outposts and a base for scientific research.

According to documents declassified in 1996, Camp Century was a preliminary camp for Project Iceworm, whose goal was to install a vast network of nuclear missile launch sites that could survive a first strike. Missiles were never fielded at the facility and obtaining the necessary consent from the Danish Government to do so was never broached.

The camp operated from 1959 until 1967. It consisted of 21 tunnels with a total length of 9,800 feet (3.0 km) and was powered by a nuclear reactor. Project Iceworm was aborted after realization that the ice sheet was not as stable as originally assessed, and that the missile basing concept would not be feasible. The reactor was removed and Camp Century later was abandoned. However, hazardous waste remains buried under the ice and has become an environmental concern.

Ice core samples from Camp Century were used to create stable isotopes analyses used to develop climate models. Analysis of soil contained in the samples suggests that the site was ice-free as recently as 400,000 years prior, indicating a much reduced Greenland ice sheet and therefore much higher sea levels. Since 2017, the Geological Survey of Denmark and Greenland has maintained a climate monitoring presence at Camp Century with the Camp Century Climate Monitoring Program. This monitoring presence includes measuring climate variables, snow and ice temperatures, and ice-penetrating radar surveys of the subsurface debris and contaminant field.

As explained by the United States Department of Defense to Danish officials in 1960, the purpose of Camp Century was to test various construction techniques under Arctic conditions, to explore practical problems with the PM-2A semi-mobile nuclear reactor, and to support scientific experiments on the ice cap.

Construction on the camp and the sub-glacial nuclear reactor began without explicit permission from the government of Denmark, leading to a political dilemma for Prime Minister H. C. Hansen.

The camp was in operation until 1967, when shifting ice caps made habitation impossible. Subsequently, the camp was abandoned and the remains of the facility were buried by the ice caps and ultimately crushed by them.

Camp Century was designed as an arctic subsurface camp and the cut-and-cover trenching technique was used for its construction. The layout of the camp consisted of a series of parallel main trenches in which buildings and other structures were housed. With appropriate maintenance, the camp design had a projected lifespan of ten years. It was manned for five years and abandoned after eight years.