The residents of the Neighborhood of Make-Believe live without much fanfare within the Pittsburgh Children's Museum.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

A 19th-century smallpox cemetery is being reclaimed by scrub forest and sand dunes.

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.

Forgotten under the construction of a new urban roadway is a small, abandoned part of town.

A remote horde of architectural treasures fit for Indiana Jones.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

Where pardoned turkeys once spent their all-too-brief final days.

The U.S. Army's giant warehouse of war art includes Hitler’s watercolors and Norman Rockwell oil paintings.

A memorial to a shareholder activist feared by CEOs around the United States.

Conveniently located within binocular range of a nuclear bunker, the "summer camp" area was a painfully obvious spy house.

There's a crumbling old mansion inside the Smithsonian National Zoo.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

Once on display alongside a giant Gumby, it’s as tall as a nine-story building when fully extended.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

The remains of a century-old mansion that met a fiery demise years after it was deserted.

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

These ornate manhole covers were used for a now-forgotten purpose.

These abandoned waterworks are crumbling into the Potomac River.

Now nearly abandoned, Kaskaskia was once the capital of Illinois and one of the most important towns on the upper Mississippi.

When it comes to handsignals (and colonialism) rock always beats scissors.

Two hundred tons of pioneer artifacts were painstakingly recovered from a shipwreck at the bottom of the Missouri River.

A collection of artifacts from Maryland's maritime past.