This abandoned NASA launch site is now a memorial to a trio of astronauts who were killed there.

Intertwined, interspecies trees which locals believe can grant boons to lovers.

It's a pretty creepy lock-up.

The snowbirds here are circus sideshow performers.

Two men built this castle on the Florida coast as an artistic “landscape sculpture.”

The first custom-designed building to showcase the works of Dale Chihuly is a wonderland of glass and light.

An 18th-century Spanish watchtower made entirely of seashell and concrete.

A luxuriant botanical garden below sea level.

A tribute to Ponce de Leon's supposed quest for eternal youth.

A luxurious 1880s hotel with its fair share of Tiffany stained glass, Edison electricity, and of course, ghosts.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

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

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

It was once the base for a series of domestic terror attacks.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

Through the decades, Black music stars have performed at this historic hub for music and the arts.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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