London's marvelous wildfowl reserve along the Thames.

Now owned by the National Park Service, this location was once home to illegal boxing matches.

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

New York City's only wildlife rehabilitation center treats more than 3,000 feathered and furry patients each year.

Con Edison’s exotic and heat-loving pests.

Little Red Lighthouse under the George Washington Bridge.

This Dutch Colonial home is the oldest remaining farmhouse in Manhattan.

Once America's longest-manned military fort, now an abandoned hulk.

The end of the 4 Line is also the end of the line for 300,000 souls in one of NYC's most illustrious cemeteries.

During the holidays, a vintage subway train whisks New Yorkers back in time.

Ride the subways of yesteryear.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

Roman-era ships unearthed...

Rome's ancient Etruscan rival, now a park full of ruins.

The underground sanctuary of a mysterious ancient cult.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

Tell this pair of "love-inviting" cats in Ginza your romantic hopes.

These artifacts were discovered during the construction of the airport, with some dating back to the Neolithic period.

Get hands on with the technological marvels of the Classical world.

This ancient statue of Dionysus lies unfinished and abandoned in one of Greece's oldest quarries.

The partially submerged ruins of a white marble quarry used in ancient Greece for over 1,200 years.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.