Disks are rolled out onto the south lawn to absorb the impact of Marine One's wheels like giant coffee coasters.

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

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Largest Roman Catholic church in North America.

A line of blue paint marks the route of the inaugural parade.

Decades before the scandal, this staircase on the river was a literal "water gate."

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

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

This grand gothic brewery has been pumping out suds for over a hundred years.

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

The hidden offices underneath Memorial Bridge have been locked up since 1976.

A celebrity from the late Cretaceous period.

People escaping slavery may have hidden inside a corpse vault.

Before Nixon, "watergate" meant canals.

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

A Spiritualist house of worship where believers communicate with the dead in the spirit world.

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

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

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

The most accurate timepiece in the world.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

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

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

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