A wondrous old library overlooking the nation's capital.

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

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

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.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

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

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

Crumbling hotel echoes with the sounds of the '30s.

A Texas-sized particle collider that was abandoned due to its Texas-sized budget.

Decaying military base deactivated in the 70s is now visited by urban explorers and military enthusiasts.