This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

The land is home to swimming ponies and a legendary 18th-century treasure.

The whole world in one water tank.

The house where John Wilkes Booth conspired with his co-conspirators.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

A much-maligned monument to teetotalism.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

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

Disney's abandoned animal island is now an overgrown ruin that was almost the coolest attraction ever.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

These unusual rooms on wheels are holdovers from the 1960s.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

This Virginia railway overpass is said to be haunted by a serial killer in a rabbit costume.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

The rogue roots are gradually consuming some of the historic marble grave markers.

The naval commander’s proudest moment in battle is memorialized in this unique tomb at Arlington Cemetery.

A cablecar-station-turned-revolving restaurant with 360-degree views of the Swiss skyline.

Home to items never before seen by the public.

There’s a hidden military meme engraved on the World War II Memorial.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.