These overlooked ruins give an intimate look at the Inca Empire's urban planning prowess.

A small town Romanian cemetery filled with darkly humorous gravestones.

A deserted hodgepodge of experimental structures designed by nearby university students.

Two men built this castle on the Florida coast as an artistic “landscape sculpture.”

15 monolithic temples emulate an eroding sand castle.

A palatial sculpture park was built illegally and in secret by a self-taught artist over 36 years.

Extraordinary sculpture garden created by an eccentric English poet.

Homemade outdoor church and sculpture garden decorated with glass shards.

This ancient Spanish castle sits high upon a hilltop.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Naturally protected city carved from a rock face.

Rock-cut cave complex filled with ancient Buddhist artwork.

Hydraulic systems in an ancient underground Iranian city.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

A hand-built folk art installation covered with messages of God's love.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

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