An abandoned munitions storage facility with a rich architectural history.

In the middle of a Vienna square, Roman ruins dating back some 2,000 years are on display.

People escaping slavery may have hidden inside a corpse vault.

Coins and medals straight from the mint await visitors to this shop in the nation's capital.

Constructed by the younger brother of George Washington.

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

A sculpture park of the tossed aside relics of the USSR, from Stalin to a massive Soviet emblem.

The oldest existing one-room brick schoolhouse in Loudoun County.

John Tyler never got to be buried at his beloved home, but every pet his family owned since has been.

This small cemetery remains hidden behind a recreation center.

A piece of baseball history is preserved in a Pittsburgh parking lot.

Take a dip beneath the stalactites in this amazing cenote.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

Once damaged by Hurricane Agnes, this bridge is now on the National Register of Historic Places.

This statue of the famed author, actor, and journalist is made entirely of screw-nuts.

Once an ancient sea, this landscape of rocky ravines is filled with the fossils of ancient marine life.

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

It took more than 20 years and a sharp eye for one man to assemble this quirky collection.

The only remnant of a small mining town is an abandoned railroad tunnel that is steeped in ghostly lore.

Rare recess caves fill this unbelievably beautiful Ohio park.

The mounds at this site were reconstructed with the help of archaeologists and historians.

This suburban house is made of dirt, and almost sparked a revolution in home construction.

The local community brought back this land to transform it into a nature preserve.

More than 350 million years ago, western New York was covered in a vast sea. Today, you can dig up the remains of the plants and animals that lived there.