BREN Tower was a guyed steel framework mast, 1,527 ft (465 m) high, on the Nevada Test Site in Nevada, USA. "BREN" stands for "Bare Reactor Experiment, Nevada."[1] The structure was owned by the Department of Energy and maintained by National Security Technologies. Access to the tower area had been closed since July 2006. No reason for the closure has been given. As part of the Nevada Test Site, it was also located in restricted airspace (R-4808N).