Ancient paintings known as the "Sistine Chapel of Cave Art."

Blackfoot petroglyphs of southern Alberta which date back as far as 7000 B.C.

Inside a former cabaret, seven floors of erotic art.

12,000 sq. ft. museum tracing erotic art from antiquity to modern times.

Living towers made of people that are now recognized by UNESCO.

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

One of the most unusual geological features, recognizable from a dozen hit movies.

Underwater art project will double as a massive artificial coral reef to help regenerate the damaged ecosystem.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

A darkly erotic open-air statuary in Catalonia.

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