A former mental hospital founded in the 1930s by a eugenicist who advocated for the forced sterilization of patients.

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

Thomas Jefferson's estate is home to hundreds of varieties of historic fruits and vegetables.

The ruins of this Thomas-Jefferson-designed mansion have been left to crumble since the Christmas Day they burnt down.

The only recreation of William Shakespeare's indoor playhouse.

Almost half-way between the Equator and North Pole.

A metal ring in the middle of the road marks the exact spot where the Soviet satellite crash-landed in 1962.

A chilling disappearance (and rescue) of a child uncovers a geological mystery.

A little piece of Paris in the sultry south of the U.S.

The world-record holder for the longest bridge stretching continuously over water.

Once the site of a Native American harvest festival, this humble clearing later played an invaluable role in the birth of jazz.

A massive sea stack famous for its appearance in The Goonies.

100-year-old shipwreck you can walk up to at low tide.

A Roman-style column in Oregon hides a spiral staircase inside.

You might recognize this historic Oregon mansion from its appearance in 'The Goonies.'

This vintage train once gave new meaning to “swimming upstream.”

Before its closure in 2002, this South Dakota mine was the largest and deepest gold mine in Western Hemisphere.

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

A plaque recognizes "unquestionably the most widely published photograph in rural electrification history."

The first declared National Monument in the United States.

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

This erect, phallic geological spire wasn't always named so domestically.

An experimental, automotive replica of Stonehenge.

The oldest extant wooden jail in South Dakota and possibly the United States.