Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

These abandoned waterworks are crumbling into the Potomac River.

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

They sort through millions of dollars worth of diplomatic gifts on behalf of the government.

The district's only illusionarium supports free writing programs for local students with every purchase.

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

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

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

A derelict bit of transportation infrastructure hidden in the woods.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Home to items never before seen by the public.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

The site of the climactic scene from the classic horror film is now a historic landmark.

The United States Capitol's former columns still stand.

An abandoned stretch of highway, deteriorating next to the operational one.

The graffitied ruins stand hidden within the Pennsylvania woods.

This public space is speckled with the eerie remnants of a defunct amusement park.

The ruined remains of a coal mining ghost town are hidden within the woods.

Once America's longest-manned military fort, now an abandoned hulk.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

This peaceful gem in upstate New York was chosen as the future home of the 14th Dalai Lama's Library and Museum.