World's first "penitentiary," meant to be humane, drove men insane.

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.

This neo-Gothic former auto showroom is one of the few remaining reminders of Brooklyn's "Automobile Row."

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

A sculptural commentary on capitalism pokes up from the East River.

The most confusing clock in New York.

There must be a pun in this haystack somewhere...

This futuristic airport terminal was abandoned for decades before reopening as a hotel—with a vintage plane of its own parked out back.

Lie in a hammock where George Washington stood.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

A bit of retro transportation flair preserved in the world's largest department store.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

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

One of only two commuter aerial tramways in the United States.

Elevated freight railway turned wildly successful urban park.

An architectural oddity hides in plain sight on this iconic London bridge.

Scattered throughout London are ancient remnants of the city's former bounding wall.

London's smallest police station is barely the size of a phone booth.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

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

This stunning concert hall has become a symbol of Iceland's national recovery.

Three columns of volcanic rock shoot out of the ocean.

The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.