Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.

The national park was once a plantation estate.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

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

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

A rotating cast of guys and dolls in front of a Washington, D.C. building.

Washington's iconic carousel has a nice piece of Civil Rights history.

Before Nixon, "watergate" meant canals.

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

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

There’s a hidden military meme engraved on the World War II Memorial.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

This poor little statue is the most vandalized memorial in Washington.

Decades before the scandal, this staircase on the river was a literal "water gate."

A much-maligned monument to teetotalism.

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

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

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

The most accurate timepiece in the world.

Art deco landmark on the outskirts of Washington, D.C.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.