The world's largest military aircraft cemetery.

The remnants of an early American attempt at missile defense.

The bomb-ravaged remains of of a colossal Neptune.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

A six-story-tall golden pyramid, surrounded by a moat.

An overlooked and unassuming engineering marvel.

"Girl in a Wetsuit" is what happens when a sculptor has to find a way around a 100 year old copyright.

The largest of London's subterranean rivers and once a mad, bad center of London life.

An emerald-green grotto just a short trip from Austin.

An intriguing three-sided folly is a testament to one man's devotion to Catholicism and the number three.

Ruins of the Crusaders' headquarters.

The largest freshwater lake in the Florida Keys.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

The world's largest drain sits below the city of Kasukabe, Japan.

Amazing pre-Civil War ruins alongside a shallow, rocky river that hosts beautiful (but endangered) lilies.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

A collection of outdoor mystical statues paying homage to indigenous Australians and ecological stewardship.

A crumbling hospital from the 1850s on Roosevelt Island.

Odd, decrepit fountain honors Chicago author who had mixed feelings about his hometown.

The remains of Crystal Palace Great Exhibition of 1851.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

Concrete strongholds stand guard over the Golden Gate.