"Nightline" delves into the secrets of the highly restricted U.S. Air Force base. Area 51 has been synonymous with alien life conspiracies and military cover-up theories, although the U.S. Air Force has maintained it is a flight testing facility connected with Edwards Air Force base in California. This satellite image shows the remote, secret military installation in the Nevada desert. Tune into "Nightline" tonight at 11:35 p.m. ET/PT. (Courtesy Google Earth/GeoEye)
View the full slideshow
Want to see more stunning and inspiring images?
GeoEye Facebook Fan Page
@GeoEye on Twitter
GeoEye's Flickr photo stream