The world's second-largest sundial, made entirely out of stone.

A mysterious castle built as a monument to lost love.

A bizarre roadside attraction and the first instance of miniature golf in the world.

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

Enormous lake at the bottom of a unique cave system.

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

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

You can climb to the summit of Black Mountain, as long as you sign the waiver.

This boulder stays on its mountain thanks to a huge chain and on the map due to local legend.

Moonbows over Kentucky.

The world's longest known cave system.

The largest earthwork effigy in the world.

The longest navigable underground river in the United States is home to countless blind and albino animals.

A flamboyantly decorated bridge signals diversity and fellowship at the entry to Indianapolis' Broad Ripple Village.

An authentic replica of an Asian temple and garden hidden amongst the natural beauty of Hawai'i.

This black shoreline is made up of exploded lava particles.

These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

A series of waterfalls and pools that flow through the 'Ohe'o Gulch and into the ocean.

Take shelter from Hawai'i's tropical heat under the massive canopy of largest Banyan tree on the island.