Nevada National Security Site
A former nuclear testing site may not be everyone's idea of a good time, which is just fine by the United States Department of Energy which operates the 1,360 square miles of desert and mountains that were previously known as the Nevada Test Site. Its public tours (which are free) happen only once a month, offer an extremely limited number of spots, and fill up quickly. If you do manage to snag a reservation, you'll venture about an hour outside of Las Vegas and cover 250 miles of NNSS terrain, including Frenchman Flat, site of Able, the area's first atmospheric nuclear test on January 27, 1951. Just don't expect to bring home any souvenirs; cameras, cell phones, laptops, and other electronic devices are not allowed, nor are shorts, skirts, or sandals.
Getting there: Though all 2014 tour dates are already full, you can add yourself to the wait list by completing an official "badging form," which can be downloaded online, then faxing or mailing it back to the Department of Energy's Nevada Field Office.