Underwater art project will double as a massive artificial coral reef to help regenerate the damaged ecosystem.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

The narrowest street in Canada was once a spot for dastardly doings, now a historic piece of Chinatown.

This spectacular track has run continuously since 1882.

A century-old network of freight tunnels underneath the city's historic business district.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

This working replica of the 'Friends' coffee shop is more accurate to the show than the set itself.

The world's longest outdoor escalator takes visitors to the top of China's largest dam and is also shaped like a dragon.

The once highest point in China blends symbolic design with a kick of adrenaline.

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Lost subway station nestled beneath Toronto's busy commuter line.

A well-preserved network of cavernous tunnels have spent silent centuries removing Toronto's waste.

These ornate manhole covers were used for a now-forgotten purpose.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

A popular European tradition makes its way to the states on one of America's most famous bridges.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

Try not to get slimed in Tribeca.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.