This is not your typical jungle gym.

Community bookshelf of 25-foot-tall book spines.

The history of the treatment of mental illness, illustrated in all its gory detail, and housed in an asylum.

A short boardwalk through a swamp leads to the spot from which the Louisiana Purchase was surveyed.

The remains of the first public diamond mine in Arkansas.

Twenty-year effort to raise a castle using tools and techniques from the 13th century is now abandoned in the Arkansas woods.

A mysterious light floating in the trees of Arkansas may be a piezoelectric effect.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

Site of the 1879 Cheyenne Outbreak and the site where famed Sioux chief Crazy Horse met his fate.

The same security that protects our nukes accidentally protected a gentle herd of antelope.

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

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.

A monument to the egos of two railroad magnates that fell into decline along with their careers.

Surrounded by a hundred mile radius of billboards, Little America is a roadside attraction whose primary appeal is hospitality.

Miraculous tree that seems to sprout out of solid rock.

Long before guestbooks and hotels, frontier travelers signed their names on this rock face.

This prison-turned-museum is a remnant of the Old West's grizzly, violent past.

One of the smallest towns in the United States.

Devilish landscape, once cinema home to giant alien bugs, now derelict roadside attraction.

A museum, walk-through diorama, and library nestled under one castle-like roof.

Yes, this monument is aware that it is about 20 miles away from the actual center of the United States.

Thanks to a loophole in property ownership, this alleyway has become a cacophonous street gallery.

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.