Collapsing castle on the Hudson river was once the storage site of military surplus business.

An ideal wedding spot that is almost too ideal.

Once the world's largest reinforced concrete structure, this abandoned bridge now beckons urban explorers.

This huge, disused viaduct is now a crumbling concrete underworld of covered in years of graffiti.

A giant pair of thick black glasses mark the tragic demise of a trio of rock and roll legends.

This remote island in Iowa was abandoned after being devastated by flood.

Picturesque and haunting, these 160-year-old stone ruins on top of a bluff are the only remains of a settler's legacy.

Covering 37 subterranean acres, this Armillaria gallic is a famous fungus with its own festival.

The eerie ruins of a remote abandoned hamlet said to be founded by the survivors of a shipwreck.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

This tiny New Jersey village has lived many lives but seems determined to remain a ghost town.

In the woods of New Jersey lie the ruins of a munitions village abandoned after World War I and the remnants of a 1920s wooden racetrack.

The site of one of history's most indelible and horrific tragedies.

Two tall rocks sit at the center of this site, once the home of a large Ancestral Puebloan community.

No one knows exactly how deep the world’s deepest geothermal hot spring is.

A small collection of iguana-infested ruins hides amid Cancún's bustling hotel zone.

An ancient system of freshwater caves filled with animal bones, including that of species long-extinct.

This abandoned iron furnace was one of the first to use coke—a type of high-carbon fuel—to make iron.

An abandoned railroad tunnel transformed into a creepy path for hikers and cyclists.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

The ruined remains of a coal mining ghost town are hidden within the woods.

A hidden piece of Altoona's railroad history in a long-forgotten abandoned town.

This dramatic rail curve was once the target of a failed Nazi attack.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.