This forgotten boat elevator was an engineering marvel in its heyday.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

A historic arena where the Beatles played their first concert in the U.S.

A diminutive plaque recalls the treetop sniper who almost killed Abe Lincoln.

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

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

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

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

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

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

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

Sit where JFK proposed to Jackie or where Nixon dined on meatloaf at this storied pub.

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

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

This restaurant has been a haven for D.C.'s LGBTQ community since the 1950s.

A clone of a cloned tree that was so important it allegedly had its own guards.

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

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

The most accurate timepiece in the world.

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 hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

A computer bug so primitive it was an actual insect.

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

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.