A painfully obvious spy house sits right across the street from the Russian Embassy.

Born a slave on the Arlington estate, Parks dug the first graves at Arlington National Cemetery, and was buried there, too.

A wondrous old library overlooking the nation's capital.

Right next to departures—how convenient!

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

Rumor has it the hot dog stand was targeted by two Russian nuclear missiles.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

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.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

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

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

The early data processor factory founded in Washington for the 1890 U.S. Census went on to become IBM.

A celebrity from the late Cretaceous period.

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

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

Before Nixon, "watergate" meant canals.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

A portal into the bricked up canal that runs through the heart of Washington D.C.

A historic ruin just 20 feet away from a busy highway onramp.

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

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

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

People escaping slavery may have hidden inside a corpse vault.