This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

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

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

Try not to get slimed in Tribeca.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A terrific purveyor of natural history objects and curios.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

This one has sailed five times as far as Sir Francis Drake's famous ship.

The Columbia Road Flower Market is now open every Sunday, rain or shine.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

Public access to clean drinking water was an instant hit among the masses.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

London's old-school healing garden.

Eighty million natural history specimens call this gargantuan museum home.

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

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

A toy store with a century-long history preserves the craftsmanship of playthings of the past.