This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

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

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

A wondrous old library overlooking the nation's capital.

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

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

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

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

The most accurate timepiece in the world.

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

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

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.

At 207 feet, one of the world's longest continuous escalators.

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

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

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

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

A secret greenspace hides atop a Capitol parking garage.

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

A nostalgic bibliographic gem.

This unassuming passageway played a key role in one of the most important events in U.S. history.

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

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.