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

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The fairy tale castle of the "fairy-tale king."

A gargantuan crystal kingdom.

These azure waters were thought to lead to the Mayan Underworld.

Extraordinary sculpture garden created by an eccentric English poet.