These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

The glowing blue Nymphaeum of Emperor Tiberius.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Stalactites and stalagmites in a beautifully lit cave.

Roadside collection of 65,000 signs.

Mining town from the late 1890s, once home to Calamity Jane.

This partially completed dam was simply abandoned after nearly destroying the city it was built to service.

This stretch of Canadian road was named after a nickname that stuck so hard the city had to keep it.

Ice roads, deep holes and 3,500 pounds of diamonds.

What happens when a sculptor has to find a way around a 100-year-old copyright.

This massive and unusual rock formation near Okotoks is the world's largest known glacial erratic.

The once highest point in China blends symbolic design with a kick of adrenaline.

A recently restored Shoreditch landmark with ties to Jack the Ripper.

Ruined pieces of stone and a swimming pool are all that remain of an amusement park swept away by a flood.

This empty Victorian manse on Staten Island is said to be haunted but is actually a real life crime scene.

A historic bridge with a lovely acoustic anomaly.

Skeletons, medical artifacts, and other obscure and precious treasures all displayed in a wooden pharmacist's cabinet.

Walk over a 150 year old manhole.

Planes, trains, and automobiles have all been sunk as attractions at this Illinois diving spot.

This massive neon wheel is the only one of its kind to be built over a bridge.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

This tall Massachusetts folly got its name thanks to all of the purple prose its vistas inspired.

An apocalyptic seismic event creates a deadly chain reaction that ends with a 6-mile long lake developing within weeks.

Figures of unknown origin carved into the surfaces of underground caves.