Groom Lake is a salt flat in Nevada used for runways of the Nellis Bombing Range Test Site airport (KXTA) on the north of the Area 51 USAF military installation. The lake at 4,409 ft (1,344 m) elevation is ~3.7 miles (6.0 km) from north to south and 3 miles (4.8 km) from east to west at its widest point. Located within the namesake Groom Lake Valley portion of the Tonopah Basin, the lake is northeast of Papoose Lake's S-4 (Sector Four) location and ~25 mi (40 km) south of Rachel, Nevada.

Lead and silver were discovered in the southern part of the Groom Range in 1864, and the English Groome Lead Mines Limited company financed the Conception Mines in the 1870s, giving the district its name (nearby mines included Maria, Willow and White Lake). Also, the historical town of Rosswell was located here until evacuation of the US Military. The interests in Groom were acquired by J. B. Osborne and partners and patented in 1876, and his son acquired the interests in the 1890s. Claims were incorporated as two 1916 companies with mining continuing until 1918 and resuming after World War II until the early 1950s.

Robert Scott Lazar or Bob Lazar (born January 26, 1959, in Coral Gables, Florida, United States, to Albert Lazar and Phyllis Berliner), has claimed to have worked from 1988 until 1989 as a physicist at an area called S-4 (Sector Four), allegedly located near Groom Lake, Nevada, at the location also known as Area 51. According to Lazar, S-4 served as a hidden military location for the study and possible reverse engineering of extraterrestrial flying saucers. Lazar says he saw nine different discs there and provides details on their mode of propulsion. However, his credibility has come under fire after "schools he was supposed to have attended had no record of him, while others in the scientific community had no memory of ever meeting him."

Lazar claims to hold degrees from the California Institute of Technology and Massachusetts Institute of Technology. In 1993, the Los Angeles Times looked into his background and found there was no evidence to support those claims.Stanton Friedman was only able to verify that Lazar took electronics courses in the late 1970s at Pierce Junior College. The Times did discover that in 1990 Lazar had pled guilty to felony pandering, when he installed a computer system for a local brothel, declared bankruptcy and listed his occupation as self-employed photo processor on documents. A 1991 Times article reported, Lazar was "on probation in Clark County, Nevada, on a pandering charge. His educational and professional background cannot be verified -- a fact he attributes to government deletion of records." However military officials claim Lazar never worked in any of their facilities.