What is this mysterious huge tower at Area 51 spotted on Google Earth?

Around 83 miles northwest of Las Vegas lies Area 51, the classified military base where new aerospace technology is tested and—depending on your appetite for conspiracy theories—a high-tech facility where extraterrestrials chill on ice as their crashed craft are reverse engineered. Recently, a new feature was spotted on the Google Earth image of Area 51: a huge triangular black tower.

You can see the structure for yourself at 37°14'46.5"N 115°49'24.0"W but maybe don't try to drive over there as They aren't fond of unanounced visitors. After all, the truth is in there.

Previously:
• Souvenir 'Area 51' license plates causes problems for owner of official 'Area 51' vanity plate
• Watch Bill Clinton talk about UFOs, Area 51, and Roswell
• FBI and Airforce in full riot gear raid home of Area 51 YouTube
• Funny Area 51 'user reviews' on Google Maps