A rapidly disappearing glacier filled with extinct grasshoppers, perfectly preserved in the ice.

Around half a million years ago, these magnificent columnar basalt cliffs were formed from cooling lava.

An architect's childhood fantasy treehouse made real.

The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

Native Americans built this circle of stones, which was used to predict astronomical events.

This beautiful ancient site is dotted with perforated sandstone pillars considered sacred by some Native American groups.

Chef Lawrence West serves up Indian tacos, wojapi, and other Lakota dishes at the brick-and-mortar incarnation of his popular food truck.

Every president in history is immortalized in bronze in downtown Rapid City.

A waterfall 600 ft. inside a mountain, once the bane of gold miners, is now a spectacle of nature.

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

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

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

Other-worldly rock formations and ancient fossils abound in this unique stretch of Nebraska badlands.

A rancher expanding a natural spring for his cattle came up with bones – lots and lots of them.

A fascinating collection of art made from petrified wood and fossils by two octogenarian twin brothers.

The center of the only hemisphere that awards visitors with a commemorative coin.

One extremely determined man's homemade universe.

Strange physical sensations and optical contradictions keep visitors coming back for more.

Located in a Civil War era building, this café is engrained with the spirit of Edgar Allen Poe.

This 38-drawer structure claims the superlative title, but it isn't the world's only giant filing cabinet.

It took over 100 years to decode this enigmatic epitaph for two buried brides.

305 homemade stone stairs wind their way up the Hamilton escarpment.

More than 350 million years ago, western New York was covered in a vast sea. Today, you can dig up the remains of the plants and animals that lived there.

A natural gas leak provides a flickering flame beneath a waterfall.