The final residence of an educator, civil rights leader, and presidential advisor was also the first headquarters of the National Council of Negro Women.

The word "Watergate" will forever be associated with the infamous scandal in 1972, but this fountain is famous in its own right.

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.

This fertility idol of questionable authenticity inspired an iconic Indiana Jones artifact.

A secret greenspace hides atop a Capitol parking garage.

Also known as the Founding Church of Scientology.

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

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

100 years later, they're still down there.

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

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

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

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

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

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

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.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A tiny piece of the Moon is embedded in this stained glass masterpiece.