What's left of the ruins of the 1893 Columbian Exhibition, or World's Fair, also known as the White City.

The world's longest known cave system.

The first full-scale tunnel built in America is short but scenic.

Electrical pylon in the shape of Disney's beloved mouse.

A monument celebrating the idea of reaching inaccessible places.

A historic presidential getaway on the continental United States' southernmost island.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

The birthplace of American international flight service has been turned into a celebrity's microbrewery.

"We Seceded Where Others Failed."

The famous boat that once ferried Bogart and Hepburn still floats in Key Largo after being abandoned for years.

In memory of the 110 victims of ValuJet Flight 592 that crashed in the Everglades.

A self-explanatory attraction allows fans to respectfully remember and honor a comedy legend.

The site where Confederate president Jefferson Davis was defeated has been marked with a bust... that leaves that part out.

The highest point in North Carolina and the United States east of the Mississippi River, Mount Mitchell is named after argumentative explorer Elisha Mitchell.

Bad farming practices caused this unnatural natural wonder.

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

The oldest bridge in South Carolina may have been designed by the same man who created the Washington Monument.

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

More than five miles of underground passageways.

Once decrepit and slated for demolition, now one of the longest pedestrian bridges in the world.

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

This historic train station has been converted to a locomotive themed hotel.

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

FDR hoped to find a cure for polio in this Georgia town's warm springs.