Area 4 — This area, within the Nuclear Test Zone, occupies 41 km2 (16 mi2) near the center of the Yucca Flat basin. Area 4 was the site of five atmospheric nuclear tests conducted between 1952 and 1957. From the mid-1970s through 1991, a total of 35 underground nuclear tests were conducted in Area 4, mainly in the northeast corner. Two of these tests involved the simultaneous detonation of multiple devices in the same emplacement hole. The Big Explosives Experimental Facility (BEEF) is a hydrodynamic testing facility, located at the Department of Energy's Nevada Test Site in Area 4, about 95 miles northwest of Las Vegas, Nevada. The need for the BEEF site originated when, due to community encroachment near the Lawrence Livermore National Laboratory (LLNL) facility in Livermore, California, DOE was no longer allowed to perform large high explosive experiments at the facilities Site 300, Shaped Charge Scaling Project. Therefore looking at the Nevada Test Site as a location to continue to perform these large high explosive experiments, two earth-covered, two-foot thick steel reinforced concrete bunkers, built to monitor atmospheric tests at Yucca Flat in the 1950s, were located and found to be ideally configured. The facility consists of a control bunker, a camera bunker, a gravel firing table, and associated control and diagnostic systems. The facility has conducted safely conventional high-explosives experiments using a test bed that provides sophisticated diagnostics such as high-speed optics and x-ray radiography on the firing table, while operating personnel are present in the bunker. The September 2002 Watusi experiment sought to show that existing seismic and infrasound sensors at the test site and across the West that were used in the days of underground nuclear testing still can detect and characterize explosions accurately. The yield of the experiment was equivalent to approximately 37,000 pounds of TNT. It took place at Lawrence Livermore National Laboratory's Big Explosive Experimental Facility, or BEEF, about 12 miles east of the test site's central Control Point.

Think that pyramidal structure is one of the monitoring bunkers?