A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

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

Famously misunderstood wonder of the ancient world

Northern Ireland's Brobdingnagian stepping stones.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The ghostly remains of an accidental sea.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

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

A huge musical instrument played by the ocean.

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

Paris' fabled purveyor of exotic taxidermy and natural history curios.