What you see on the pictures below is a massive concrete lid to a 107 m diameter nuclear waste trash can on a beautiful island in the middle of the Pacific ocean.
Click on image for a larger view :
After WW2 the locals were evacuated, often involuntarily, and the atoll was used for nuclear testing as part of the U.S. Pacific Proving Grounds.
Beneath the concrete dome on Runit Island (part of Enewetak Atoll, Marshall Islands), built between 1977 and 1980 at a cost of about $239 million, lie 111,000 cubic yards (84,927 cubic meters) of radioactive soil and debris from from 43 atomic and thermonuclear explosions on Bikini and Rongelap atolls between 1948 and 1958. The dome covers the 30-foot (9 meter) deep, 350-foot (107 meter) wide crater created by the May 5, 1958, Cactus test.
The people began returning in the 1970s, and on May 15, 1977, the U.S. government directed the military to decontaminate the islands. This was done by mixing the contaminated soil and debris from the various islands with Portland cement and burying it in one of the blast craters.
The U.S. government declared the islands safe for habitation in 1980.
coordinates : 11°33’09.10″N 162°20’50.21″E
The concrete dome during its construction :