A replica viking ship from the Chicago World's Fair is still in dry dock in an Illinois park.

The face of a woman pushes its way through the earth.

Arguably the best example of an authentic Dutch windmill in the United States, rivaling its counterparts in the Netherlands.

Shop of curiosities with a dinosaur museum tucked in its basement.

A six-story-tall golden pyramid, surrounded by a moat.

Moving, mind-blowing metal sculpture work of an outsider artist.

Hidden away in the city of Madison, Wisconsin is a nearly forgotten home that Frank Lloyd Wright built for a childhood friend.

A museum celebrating the self-taught artist-environment builder.

A bedazzled house and crown "jewel" of outsider artist Loy Allen Bowlin.

One lonely, modern pyramid has gone from corporate think tank to deserted boondoggle.

Inside this mountain lies several kilometers of breathtaking caves.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

An emerald-green grotto just a short trip from Austin.

Free public park and gardens filled with peacocks and peahens.

This naturally-sourced hot spring is now home to a clothing-optional resort.

The largest self-built castle in the U.S., six decades in the making.

This massive wooden building contains a giant Buddha, healing pillars, and tame deer wandering the grounds.

A salty cave excavated by elephants and the location of a deadly disease vector.

Microscopic fossils suggest Australia may be the birthplace of sulphur-based life forms.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A beautiful geyser under environmental threat.