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

The illuminated falls are a gem in North Cascades National Park.

The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A little-known hot spring haven right below the highway.

Walk the whole Mississippi River!

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The biggest pinball arcade in the world has over 600 pinball machines, and 300 arcade machines.

In the remote high desert of New Mexico, a strange array of poles beckon fury from above.

Come for the speed, leave in love with the desert.

The drama of nature in full effect in this Nevada State Park.

Moonbows over Kentucky.

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

These banned cigarette vending machines now sell little pieces of pocket-sized art.

These towering spires and glowing walls are carefully crafted from hundreds of thousands of icicles.

A hidden beach at the end of a tunnel of mangrove trees.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

A Texas cave network is home to some of the world's most spectacular-looking and bizarrely named mineral formations.

Abandoned silver mine strewn with wrecked and twisted structures.

A historic covered bridge, only one of two remaining in North Carolina.

Free public park and gardens filled with peacocks and peahens.

One of the last free public hot springs is decorated with hippie art.

Only known mainland rookery of the threatened Stellar sea lion.

America's only nuclear missile silo open to the public.