Commemorating the spot where the famous scientist fed his pigeons.

The 28-foot granite map plots the locations of 40 theaters in New York City.

Plot your trip through the city on the sidewalk.

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

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

New York City's smallest piece of private property.

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

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

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

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

Catacombs turned marketplace.

Hear the quietest sound from across the dome.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.

With over 5,000 champions, the Hall of Fame continues to draw amateur eaters.

An angular maze of concrete in Grand Rapids acts both as public art and as a staircase for fish traveling upstream.

At HopCat, a marker honors fictional creatures with the ability to travel the missing dimensions of Kcymaerxthaere.