An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

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

The hidden offices underneath Memorial Bridge have been locked up since 1976.

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

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

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.

Obscure Freemasons still live in D.C.’s largest private residence.

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.

These recently uncovered walls are all that's left of Washington, D.C's first defense contractor.

A celebrity from the late Cretaceous period.

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

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

An Industrial Revolution-era public work that purified water using nothing but sand.

Seemingly unremarkable items like empty sushi trays, chef hats, and freshness stickers are being preserved so future generations can look back on this beloved cultural import.

The "lovely red Vega" of the legendary record-settling pilot.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

There's a crumbling old mansion inside the Smithsonian National Zoo.

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

A computer bug so primitive it was an actual insect.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

It was once the base for a series of domestic terror attacks.