This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

Known as one of America's most beautiful public restrooms.

The symbolic center of Ireland, this summit also offers panoramic views of the countryside.

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

Virgil's many-mouthed gateway to the underworld.

Shoreline strewn with the remains of ghostly fallen trees.

This large Sitka spruce that appears to be floating in mid-air, has defied logic for years.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

Stroll through a wonderland of stupendous moss-covered trees.

This precariously perched fortress was once ruled by a crow-worshipping baron.

This floating garden in the sky is straight out of a fairy tale, but the real thing is nothing short of magical.

An exquisite tunnel of cascading flowers.

This massive subterranean fissure is known as the "underground Grand Canyon."

Cat art as far as the eye can see.

The famed architect designed this Minnesota gas station of the future with a lookout tower.

Travelers exchange letters with woodland creatures at this mini post office.

A speck of nature and art in one of San Francisco’s most notorious neighborhoods.

Golden Gate Park's historic collection of plants.

Nestled in the heart of San Francisco’s bustling Financial District stands a unique homage to the Mayan and Beaux Arts.

A shop full of natural curiosities, carnivorous plants, and costumed taxidermied mice.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

San Francisco's newly reopened hands-on science museum.