The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

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

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

Where the U.S. government kept its actual treasure, before Fort Knox.

The "lovely red Vega" of the legendary record-settling pilot.

The most accurate timepiece in the world.

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

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

The national park was once a plantation estate.

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

The walls of the iconic dome are hollow and have a secret stairway.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

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

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

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 childhood home of the Sultan of Swat is just a line drive away from Oriole Park at Camden Yards.

This historic lighthouse was well known for the large number of women who served as its keeper.