Mount Rushmore's hidden room plus secrets of other US attractions

Most visitors to New York know Waldorf Astoria as a swanky hotel dripping in old-school luxury. But, beyond its chandeliers, vaulted corridors and uber-luxe lobby, the hotel hides a secret or two – not least the train station that exists beneath its plushly carpeted floors. It has become known as Track 61 and was used by VIPs, including President Franklin D. Roosevelt, who purportedly wanted to hide his polio disease. There are rumors that the station is still occasionally used today too.