This Florida sinkhole hides a rainforest-like micro-environment in its depths.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

Disney's abandoned animal island is now an overgrown ruin that was almost the coolest attraction ever.

The scuba diving training facility was named for the steam that rises from the cave's chimney.

Florida might be at its most surreal in this museum devoted to the famed Spanish artist.

An underwater city for the dead.

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

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

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

The rusting remains are visible sticking out of the waters of the Delaware Bay.

Several times a year, during low tide, two pairs of historic train tracks are revealed on this New Jersey beach.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

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

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.