The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

This giant iron playfully pays tribute to an early 20th-century architectural trend.

Who needs fancy modern water slides when this giant North Carolina rock works just as well?

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

The remains of the iconic train crash from the movie The Fugitive can still be found rusting along the Great Smoky Railroad.

North Carolina's finest examples of Native American pictographs have survived for 5,000 years.

Visit this playground of waterfalls, caves and sinkholes.

Step back in time on this preserved 1800s farm.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

Enormous lake at the bottom of a unique cave system.

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

Mile-long cave system near Great Smoky Mountains.

A failed utopian experiment for British expats in the American South is now a Victorian village frozen in time.

Better known as the "Body Farm," this unique research facility has been studying how human bodies break down since the 1980s.

Knoxville’s architectural icon was the symbol of the 1982 World’s Fair, even catching the googly eye of Bart Simpson.

This former maximum-security prison is creepy, sobering, and supposedly haunted.

The secret city built by the Manhattan Project.

A bronze sculpture honors the 12 black students who attended the first integrated public high school in the segregated South.

These unusual rooms on wheels are holdovers from the 1960s.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.