Hidden behind Lincoln's head is a chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The oldest continually operating golf course in the United States.

Where the oil industry began.

The site of America's first commercial oil well essentially disappeared after the town went bust.

Priceless space junk on display in front of a local Dairy Queen.

Over 20,000 sets of spice shakers reveal the surprisingly telling history of our most basic spices.

This 19th-century building inadvertently preserved the handprints of its builders within its walls.

Mile-long cave system near Great Smoky Mountains.

In one of America’s oldest mountain ranges, a long-awaited section of a scenic highway is now open to the public.

Enormous lake at the bottom of a unique cave system.

Moonbows over Kentucky.

The first KFC is on the National Register of Historic Places.

Eight rare Corvettes are swallowed up by a sinkhole in Kentucky's National Corvette Museum.

The world's longest known cave system.

Once one of the most polluted caves in America, now an environmental success story and a museum dedicated to caves.

The oldest operating Mississippi River–style steamboat still navigates the Ohio River.

The massive, original Colgate Clock is mounted on a defunct factory building that was once a prison.

Marine fossils from the Devonian period are exposed at this park.

This site is where Lewis and Clark met and formed the Corp of Discovery with a few local men.

A life-sized recreation of the megafauna that once roamed this region is a feature at the birthplace of American paleontology.

Rabbit Hash is a heaping slice of Americana from another era, with a very peculiar origin behind its unusual name.

A former nuclear facility during the Cold War turned nature preserve.

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.