Where the U.S. government kept its actual treasure, before Fort Knox.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

Go take a picture with the inventor of the daguerreotype photographic process.

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

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

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

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

A derelict bit of transportation infrastructure hidden in the woods.

The walls of the iconic dome are hollow and have a secret stairway.

A nostalgic bibliographic gem.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

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

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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

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

Home to items never before seen by the public.

The United States Capitol's former columns still stand.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

This Los Angeles animation studio is keeping the wonder of stop motion puppetry alive.

The final resting place of a space program monolith.

Historic funicular railway, believed to be the shortest railroad in the world.