No, this is not a fleet of UFO's that have landed in the desert. It's an abandoned factory, but one built in a most unconventional manner -- as a series of interconnected concrete domes covered with polyurethane foam. The plant was built in the early 1980's to manufacture electronics circuit boards, but the venture fell through and construction was never completed. Now there's nothing inside the crumbling structures but graffiti, the wind, and the eerie echoes caused by the spherical ceilings ... which lead some people to believe the Domes are haunted!
Directions: East side of Thornton Road, 1.1 miles south of Interstate 8. The site is posted no trespassing, but the buildings can be seen from outside the fence.
Last visited: January 2010.
Standard disclaimer: Sites are described for entertainment purposes only, as they were at the time of my last visit. I can not vouch for the current condition of the site or its accessibility.