Fake subway tiles were installed to cover a design that resembled the Confederate flag—it's unclear if the resemblance was intentional.

Beautiful mosaics cover the first stations opened on New York City's newest subway line.

Stunningly detailed mosaics in a New York subway station bring life to the Weimaraners of artist William Wegman's work—and to thousands of commutes.

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.

A massive collection of petroglyphs dating back some 40,000 years.

Macabre astrological automaton clock dating to the late 1400s.

Legend says this sacred tree was a gift from goddess Athena.

Remains of the artificial harbours invented for the Allied invasion of Normandy can still be seen at sea.

In the 19th century, this was the center of Boston's Black community.

No one messes with the Massachusetts sacred cod, not this time...

This landmark cemetery in Boston was created more than 300 years ago.

Narrowest house in Boston.

A centuries-old church stands as a testament to Boston's "father of architecture."

This area was once known for being a lawless haven for rough-and-tumble sailors, earning the maritime-themed nickname "the black sea."

What was once a true peninsula has now been filled in, causing the water to recede and leaving many streetside "waterfronts" and landlocked "islands."

Two stone columns flank the grand Venice square, but there were supposed to be three.

Go inside to really appreciate this 500-year-old technological masterpiece.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

The ritual has been performed uninterrupted for nearly 700 years.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.