During Prohibition, the U.S. Congress had an "official" bootlegger, with his own Capitol Hill office.

In the basement of the U.S. Capitol Building is a hidden storage room full of ornate floor tiles leftover from the 1850s.

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

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

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

This grand gothic brewery has been pumping out suds for over a hundred years.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

This painted blacktop brings the classic arcade game to life.

Spanning an elevation of 160 feet and containing 388 steps, this is Seattle's longest staircase.

An old-timey peepshow allows visitors to gawk at some of the world's most freakishly large footwear.

This former coal gasification plant found a curious second life as a popular public park.

Couple's personal collection of pinball machines turned public pinball museum.

A walk through the historic city center, under the streets of Seattle.

An old vending machine serves up unpredictable beverages from its seemingly magical insides.

A Museum of Holography frozen in 1974.

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.

A military museum and library dedicated to the citizen soldier.

The iconic Chicago sculpture hides a beautiful and easily overlooked plaque on the backside.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

An enormous dragon scales the walls of this 17-story temple.

Abandoned 19th century homes once occupied by naval officers, soon to be demolished.

This impressive mansion in Vinegar Hill has some mysterious details in its architecture.