Elevated freight railway turned wildly successful urban park.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

A bizarre roadside attraction and the first instance of miniature golf in the world.

Massive still life just off the highway in Kansas.

Giant granite rocks standing end-to-end like a train of circus elephants.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

What was once a presidential estate is now an exotic menagerie and home to the Budweiser Clydesdales.

A four story, football field-sized, nine-grotto creation made of shells, minerals, and rare stones.

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

Less a museum than a bizarre fantasy world created by artists and engineers.

Curious rock formations in a tiny Kansas state park.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

The largest source of fossilized insects anywhere.