This ancient sinkhole-turned-healing-pool is a treasure trove of archeological discoveries and may even be the Fountain of Youth.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

The site where Poe "in great distress, and ... in need of immediate assistance" likely died.

This glamorous old building is said to have inspired the Tower of Terror.

When ecosystems collide in the arid Southwest.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

Canyon walls shrouded in ferns.

Despite the ever pressing encroachment of urban sprawl this grand New Orleans manse still stands.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

The eccentric mansion of one the most popular horror authors of modern times.

European castle ruins in an American state park are actually the product of death and grief.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

Couple's personal collection of pinball machines turned public pinball museum.

This historic "City of the Dead" lies prominently in the center of New Orleans' famous Garden District.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

This incredible collection of vintage pinball machines can be played at 25 cents a pop.

An acoustic anomaly with a mysterious cause.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

The one-stop shop for all of your superhero (or evil arch-nemesis) needs.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

America's most famous piece of self-built architecture.