Rare recess caves fill this unbelievably beautiful Ohio park.

This mysterious twin turboprop Grumman G-159 covered in graffiti has spent a decade and a half abandoned.

The ruins of a cotton mill that was burned in the Civil War are still hidden in a Georgia forest.

This intricate Hindu temple is the largest of its kind outside of India itself and was constructed like a giant puzzle.

Bad farming practices caused this unnatural natural wonder.

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

A ship that lived many lives under many names is now known merely as the "Ghost Ship."

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.

These unassuming lighthouses have seen the first reading of the Pledge of Allegiance, the first wireless transmission, and more than one mystery.

World Trade Center memorial likened to a woman's sexual organ.

Hidden deep within New Jersey Pine Barrens is a massive graffiti wonderland.

Tucked behind New Jersey's abandoned Gingerbread Castle lie the eerie ruins of a once-flourishing paper mill.

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

This massive boulder is either a unique rock formation created by glacial melt or a magic energy vortex.

World War II bunker still standing on the New Jersey beach.

Step inside Lucy, the world's largest "elephant."

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

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

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.

Each step is a mere four inches tall, said to be measured by the stride of a woman wearing a hobble skirt.

For decades, it has disappeared and reappeared as water levels rise and fall.

A field of nothing but boulders which resembles a giant's gravel driveway.

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

This secluded walking trail is a hidden gem of a Pittsburgh park.