More than five miles of underground passageways.

This simple, broken column marks the final resting place of one of America's most famous explorers.

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

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

This funicular railway rumbles along for a mile up the nearly vertical face of Chattanooga’s Lookout Mountain.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

Mile-long cave system near Great Smoky Mountains.

This replica of the Greek structure is in the heart of Nashville.

Enormous lake at the bottom of a unique cave system.

It turns out that a hurricane-prone beach is probably not the best place to house wild animals.

A luxurious 1880s hotel with its fair share of Tiffany stained glass, Edison electricity, and of course, ghosts.

WWII-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers. .

A scenic fort on the harbor protected Philadelphia from an attack that never came.

This small-town pizzeria won the Hollywood lottery.

Quirky castle designed by the American actor best known for portraying Sherlock Holmes on stage.

The highest point in Alabama was almost completely deforested, but is now home to protected towers and trees.

This statue inspired by Renoir's famous painting embodies the jovial spirit of Key West.

Bat house that has only ever housed bat for one night; they all flew away and never came back.

An octet of classic chrome trailers speared into the ground act as a tribute to the silver bullets of the open road.

These constructed wetlands naturally filter millions of gallons of treated wastewater every day.

Dedicated to the victims of one of the deadliest hurricanes to strike the United States in recorded history.

Near the ruins of a Civil War coastal fortress lies the only known African refugee cemetery in the United States.

Get up close with some alligators at this roadside farm attraction.

Flip your own pancakes in this old sugar mill within a Florida state park.