Area 51 is one of the most enduring mysteries and sources of speculation in American history.

Located inside the Nevada Test and Training Range, the flat-dry lake bed known as Groom Lake has been the home to some of the nation's most advanced espionage and weapons technology, hair-raising tales of Cold War brinksmanship, and possibly much worse, according to a new book about the top-secret military base.

In writing "Area 51: An Uncensored History of America's Top Secret Military Base," Annie Jacobsen combed through thousands of pages of declassified material on American spy plane development, nuclear testing at Area 51, and the history of the CIA and Air Force's control of the base.

In the course of her research, she interviewed dozens of men who worked or lived at Area 51 and are only now talking to one another and the public about their time there. She also interviewed one anonymous source who suggested a deeply dark side of the research conducted at Area 51: human experimentation and psychological warfare (and, of course, a high-level cover-up).

I interviewed Jacobsen, along with Jim Friedman, who was a senior field administrator at Area 51 for 13 years, and TD Barnes, a radar specialist who lived and worked at Area 51, in Nevada near the edge of the enormous testing range and base. We drove up to the gate at Area 51, talked at length about the planes and other technologies developed there and dug into the controversy surrounding the most shocking parts of Jacobsen's book.

The interviews and footage originally aired on CBS' "The Early Show," and these three videos are extra footage and longer interviews about the topics covered in the book. First, a journey down the long Nevada highway and desolate dirt road that leads to the back gate at Area 51: the most intimidating gate you've ever seen. When we got there, there was broken glass on the ground, an ominous camera gazing down at us, and absolutely no one in sight. But I could feel the weight of eyes on me with every moment we were there (and I expected a blow-dart in the back at any second!).

Finally, the most controversial part of Jacobsen's book: the story of Area 51's most enduring conspiracy theory, the Roswell UFO. The only anonymous source in her book delivered still-classified details, if you can believe them, about a disc-shaped aircraft engineered by Nazi scientists and sent by Josef Stalin as part of a psychological warfare campaign--and worse.