The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.

A brass plaque dedicated to a convicted cannibal hangs in the National Press Club, and that's not even the craziest part of the story.

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

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

A Spiritualist house of worship where believers communicate with the dead in the spirit world.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

The oldest continuously operating fish market in the United States.

When it opened during the final years of the embargo, all the drinks and cigars were free.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A historic neighborhood church is reborn as a psychedelic arts collective.

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

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

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

Thousands of well-dressed mummies below a monastery.

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Naturally preserved bodies are eerily staged throughout the crypt in varying poses.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

Anatomical cabinet holds unexpected treasures.