This outdoor gallery of graffiti-covered walls pays homage to the past, present, and possible future of street art.

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

A celebration of capitalism in Midtown.

Elevated freight railway turned wildly successful urban park.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A crumbling hospital from the 1850s on Roosevelt Island.

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

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

A Victorian cemetery in the heart of Brooklyn remains a popular mecca of morbid curiosity.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

A terrific purveyor of natural history objects and curios.

Lie in a hammock where George Washington stood.

Try not to get slimed in Tribeca.

An arcade packed with a rotating collection of unique independent video games.

A magical and peaceful ruined Cistercian abbey in what is now southern Belgium.

A visionary precursor to the Internet made of index cards.

Inside this former medieval prison is a collection of objects designed to inflict unbelievable pain and suffering on the human body and mind.

These gigantic skeletons tower over visitors and provide insight into the creatures that once ruled over Ireland.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

Experience what life was like in Ireland during the Viking and medieval ages.

A remote desert lookout offers unparalleled views of the California badlands for those who brave the trek.

This short bridge is the only thing connecting a tiny Irish island to the mainland.