An enormous pink granite batholith, long attributed with spiritual powers by the Tonkawa Indians.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

One of the Cemestos prefab homes built to secretly house thousands of Manhattan Project workers.

The secret city built by the Manhattan Project.

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

Enormous lake at the bottom of a unique cave system.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

A place where the laws of nature seem to have gone completely berserk... but of course haven't.

One of America's first dinosaur parks gives a window into Depression-era paleontology.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

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

The highest point in South Carolina was once owned by an energy company that neglected it but now the state is taking it back.

Memorializing an American tragedy of massive proportions.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

Steepest flood safety railway in the entire world.

The house that Frank Lloyd Wright "(shook) out of his sleeve at will" at the age of 86.

Frank Lloyd Wright’s most iconic home dangles over a Pennsylvania waterfall.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Rare recess caves fill this unbelievably beautiful Ohio park.

The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

Prison made famous by The Shawshank Redemption has been out of commission since 1990.

The only remnant of a small mining town is an abandoned railroad tunnel that is steeped in ghostly lore.

Down the road from where the Wright brothers lifted off is another flight tribute practically hidden from sight in the woods.

Beautiful Gothic-inspired lighthouse stands out among the run-of-the-mill striped fare on Bodies Island.