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

Half of a waterfall goes into the river while the other half seems to disappear.

A geological bull's-eye visible from outer space.

A fiery crater has been burning in the Karakum Desert since 1971.

A spectacular cave and a beguiling lake.

The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

An isolated dive site teeming with cnidarians.

The topiary maze at the Habsburg hunting lodge.

A mythically themed self-built sculpture park.

An intricately decorated tiny place of worship.

A beautiful, dense forest in the shadow of Mount Fuji, with a tragic reputation.