America's Most Wanted's set resides in this tribute to the history of crime and punishment.

A surprising, but overlooked example of geology in the middle of the nation’s capital.

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

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

Look closely and you’ll notice that the color changes a third of the way up the tower.

An overlooked memorial honoring the local Washington residents who died in World War I.

The fountains of the U.S. Navy Memorial are annually salted with water from the Seven Seas as part of a nautical ritual.

This forgotten boat elevator was an engineering marvel in its heyday.

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

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

These old doors are covered in the signatures of Rehoboth Beach artists dating back to the 1930s.

This collection of odd proofs of concept is like taking a walk through the imagination of a Victorian engineer.

This shrine dedicated to the Virgin Mary is also a tribute from a mother to her fallen son.

This historic furnace was once used to produce cannonballs during the Civil War.

One of Philadelphia's largest murals resides hidden under this bridge.

An eccentric priest's tribute to George Washington, this chapel tells the story of the American Revolution.

A hidden piece of Altoona's railroad history in a long-forgotten abandoned town.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

The elevator hidden in a smokestack on Roosevelt's yacht now serves as a monument to the former president.

Proto-CIA agents trained with grenades in the sand traps and fired machine guns from the fairways.

The wooded estate of the Forest Service employee responsible for D.C.’s cherry blossom trees.

One of the only memorials dedicated to journalists who died in combat.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.