This former coal gasification plant found a curious second life as a popular public park.

A wall of chewing gum moonlights as collective art.

A whimsical village of unique treehouses resides in a Washington forest.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

A museum dedicated to the history and exploration of both popular music and science fiction.

Stroll through a wonderland of stupendous moss-covered trees.

A 100-year-old purveyor of curiosities, curios, and kitsch featuring mummies, shrunken heads, and a Fiji Mermaid.

A walk through the historic city center, under the streets of Seattle.

A giant Troll lurks under one of Seattle's oldest bridges.

The wreckage of a World War II bomber is hidden high in the Colorado wilderness.

This eclectic collection documents the wild legacies of "America's Wickedest Street."

A collection dedicated to the treatment of disease, held in London's oldest hospital.

A tongue-in-cheek arcade where the games are based on everyday life.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.

A mental health hospital dating back more than 139 years, now features a museum.

A psychedelic labyrinth on the San Francisco bay.

Shoot for par over the bodies of the dead on this cemetery-cum-golf course.

Thirteen trees representing the original thirteen colonies were planted with soil from historic Revolutionary battlefields.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

A famous alternative culture epicenter and where Joplin serenaded young hippies.