A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

Tiki luxury on Nob Hill.

A student driver's nightmare.

Quite simply the largest tree in the world (by volume).

A fifth-century temple improbably built into the side of a cliff.

A celebration of capitalism in Midtown.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

A gargantuan crystal kingdom.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Rustic natural hot springs in the deciduous rain forest.

A giant bronze coil of feces is both a tribute to doggie defecation and a reminder to pick it up.

An acoustic anomaly with a mysterious cause.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A self-built castle made by a mysterious man.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Two thousand artifacts from around the world collected by one woman who loved to travel.

A house filled to the brim with oddities and curiosities.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

An old world fairytale-land with over 350 fairy folk figurines hidden amongst 800 year old cedars.