The story behind the mysterious symbol painted in front of the historic university's famous Rotunda.

America's first public mental health facility.

This museum explores the grim reality of life in the earliest British colonies in America.

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

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

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

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

There’s a special club house at the top for the bell ringers.

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

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

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

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

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.

Perhaps the most scandalous statue of America's first president.

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

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

The national park was once a plantation estate.