A semi-scholarly approach to sex.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

The oldest house in Washington, D.C. wasn't originally constructed in the nation's capital.

A replica of the famous memorial statue at the Normandy American Cemetery hides in an office building in downtown D.C.

Amid the sprawling Defense Intelligence Agency Headquarters is one of Washington's least accessible museums.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

‘Bush the old fire dog died of poison July 5th, 1869. RIP.’

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

An overlooked memorial honoring the local Washington residents who died in World War I.

The school tested mustard gas for the U.S. Army during World War I.

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

When it comes to handsignals (and colonialism) rock always beats scissors.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

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

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

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

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

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

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

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The most decorated dog of World War I is preserved in the Smithsonian.

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