This dig site outside D.C. is known for its exceptionally high density of baby dinosaur fossils and dinosaur eggs.

A haunting exhibit in a wildlife refuge center highlights threatened species and the conservation efforts needed to save them.

There's a crumbling old mansion inside the Smithsonian National Zoo.

The 28,000-year-old specimen is remarkably intact.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The remnants of a wooden-hulled fleet built and abandoned in WWI, now home to a thriving ecosystem.

A slab of sandstone covered with mysterious 1,000-year-old rock carvings from a vanished North American culture.

This sprawling farm was once a Cold War-era hideaway for the nation's top diplomats.

A circle of giant painted vases in the former pottery capital of the United States.

The pop art icon's gravesite is broadcast 24 hours a day on his museum's website.

The ruins of this Thomas-Jefferson-designed mansion have been left to crumble since the Christmas Day they burnt down.

This one-room cabin where the young colonel slept during the French and Indian War.

The flower-shaped temple in Virginia aims to transcend the boundaries of the world’s religions.

This park pays homage to the region's rich industrial history of brick making.

Anna Anderson spent most of her life claiming to be the lost Romanov child Anastasia.

A "hospital" where people went to be quarantined, die, and be buried in the yard.

The site of the worst mining disaster in Ohio's history.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

This abandoned dream castle and its cemetery look out over the city that once inspired their creation.

An abandoned asylum incorporated into a college campus.

Paranormal investigators claim this abandoned asylum is the most haunted spot in the eastern U.S.

There are more than 4 million bricks inside this unofficial Lego museum in a former middle school.

Constructed in 1882, this jail once housed local inmates and the sheriff's family all under one roof.

Despite its lavish ornamentation, and wholesome lifestyle of its devotees, this mountain commune has faced its share of issues.