From Route 66 to the bright lights of Las Vegas, the USA is overflowing with wish-list experiences. It also, intriguingly, has many places that can’t be experienced at all, such as top-secret military bases, high-security prisons, clandestine islands and undercover clubs. These are the hidden and off-limits spots that most people will never see – and, in some cases, that’s probably for the best.

Read on to discover some of the fascinating places in America that tourists are forbidden to visit...