Haunted dolls, macabre artifacts, and more make up the collection of the “most haunted museum in the world.”

More than five miles of underground passageways.

The world's longest known cave system.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

Visit this playground of waterfalls, caves and sinkholes.

This large cave is a summer home to thousands of bats and has a rich history dating back to prehistoric times.

A miniature city built by a single hunchbacked monk.

Thousands of unique minerals, including some of the most impressive fluorite crystals in the world.

One person's lost luggage is another person's treasure.

Large rocks have been painted to whimsically resemble wild and farm animals.

Famous for its bio-luminescent inhabitants, known as "dismalites."

An ancient cave system in Tennessee’s Appalachian foothills converted to a 1,200-person music venue.

Mysterious library of an infamous financier and spiritual seeker.

This limestone outcropping was once a ceremonial site for ancient Native Americans.

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

This park contains one of the largest concentrations of cedar glades, a unique and rare ecosystem.

The longest non-mortared wall in the country is one man's tribute to his displaced Yuchi ancestor's five-year journey to her homeland.

Home of an evil witch famous within southern folklore.

At 135 years old and counting, this historic print shop is heaven for poster nerds and music buffs.

When Motown musicians came to Nashville in the 1960s they stayed at this historic record-pressing company because hotels wouldn't host them.

This eccentric mansion museum holds a impressive collection of rare and automatic instruments.

Mutant vegetables, transgenic mosquitos, and atomic rodents span the walls of this one-of-a-kind museum.

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

A Gothic gym and community space that encourages fitness for misfits.