In 1962, a 1,527-foot tall guyed mast was built at Yucca Flat. The mast had an unusual task: It carried on its upper section an unshielded reactor mounted on a sledge. The height of the mast is approximately the same as the height at which the bomb dropped on Hiroshima exploded. The mast was designed to simulate the radiation of that bomb.

BREN (Bare Reactor Experiment, Nevada) Tower was dismantled - despite its immense size - and rebuilt at Jackass Flats in Area 25 of the Nevada Test Site, where it was later used for a series of radiation measurements called Operation HENRE (High Energy Neutron Reactions Experiment). This was after the Nuclear Test Ban Treaty banned open-air nuclear testing.

Built using 51 30-foot sections of high tensile steel, the mast is taller than the Empire State Building. To stand, the mast requires 5.5 miles of guy wires that are designed to withstand winds in excess of 120 mph. A two-person elevator inside the tower can climb at 100 feet per minute, requiring 15 minutes to get to the top, where an outside hoist is connected to lift scientific equipment.

Today, the tower is owned by the United States Department of Energy and maintained by National Security Technologies.