Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The most accurate timepiece in the world.

A haunting tribute to pioneering photographer Clover Adams.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The house where John Wilkes Booth conspired with his co-conspirators.

There’s a hidden military meme engraved on the World War II Memorial.

A nostalgic bibliographic gem.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A painfully obvious spy house sits right across the street from the Russian Embassy.

The site of the climactic scene from the classic horror film is now a historic landmark.

Home to items never before seen by the public.

A small town built on an abandoned airfield has former runways as streets and a bar and grill in an old airplane hangar.

This Wyoming town is fascinated by a particular mythical creature.

Population: 1.

The first declared National Monument in the United States.

Behind a modern brick exterior lies the oldest continuously-operating lunch-car diner in the United States.

A statue honors the genius who allegedly first took a meatball and made it into a hamburger.

Meet the "Green Monster" of Monico, Wisconsin.

The oldest continuously-operating tavern in Wisconsin used a clever loophole to serve alcohol during Prohibition.

The world's largest talking cow would like to tell you about the benefits of 100% Wisconsin dairy products, if only she still could.

A restaurant and lodge in northern Wisconsin which served as a clandestine hideout for John Dillinger and featured one of the most famous botched FBI raids in history.