The world's longest known cave system.

This defunct, fortress-like prison has been the setting for several movies.

An engraved boulder marks the spot where Patsy Cline's life ended in a plane crash.

Over a dozen Native American earth mounds dating back over 2,000 years dot this Tennessee archaeological park.

This ceremonial mound is one of the first officially recognized Native American historical sites in North Carolina.

This bright yellow relic is the final survivor of a short burst of seashell-shaped petrol pumps.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

This sanguine boulevard was named after a deadly cowboy bar fight.

An artificial crater field that trained astronauts for lunar exploration.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

This Route 66 classic sports a giant fiberglass rabbit that you can ride.

This historic national park is covered in the stunning ruins of red rock pueblos.

A stealthy Apache hideaway that became the haunting site of a mass grave.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

This smiling statue memorializes local cartoonist Bob Montana and his legendary creation.

Final resting places of a husband and wife who became famous for their claims of extraterrestrial abduction.

Massachusetts memorial to murder victim Elizabeth Short near the spot where she was born.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

Filled with history, this cemetery is maintained each summer by a few hungry goats.

Originally built in 1869, this castle is currently part of Felician University's campus.

The way these carnivorous dinosaurs are posed is an homage to a classic work of paleoart.

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

Step into Monet's world at this fine-dining restaurant in the middle of a New Jersey sculpture park.