This natural sea cave hides a small wonderland of natural turquoise beauty.

This expansive bridge in the Canadian wilderness was originally just built for friends.

Railways may have forged this quintet of lovely tunnels, but now they are open to hikers.

Traditional 15th century Chinese garden in the middle of Vancouver.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

Sleep snuggled in a sphere suspended atop the forest canopy of Vancouver Island.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

Ruins of a German Castle on top of a towering stone pillar.

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

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

A submerged archeological park still holds the wonders of a Roman Sodom.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

Started as a kitchen garden, now the second largest botanical garden in the world.

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

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

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

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A huge musical instrument played by the ocean.

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

A psychedelic labyrinth on the San Francisco bay.