The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

This ancient sinkhole-turned-healing-pool is a treasure trove of archeological discoveries and may even be the Fountain of Youth.

One of the world's tallest Ferris wheels takes visitors high above Las Vegas in a spinning party room.

Isolated atop this Balinese sea crag is a lovely Hindu temple that is said to be guarded by sea snakes.

If you were standing here on October 5th, 1950, you'd be dead.

Feral cats keeping the rodent population at bay all across Greenpoint waterfront.

A drawbridge named for a potentially intersex Polish national who fought alongside George Washington during the American Revolution, and an example of "Pulaski Red".

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

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

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

Named the fifth most beautiful building in America in 1885, this former courthouse boasts the best view in the Village.

An artist's cute bronze subway sculptures belie his violent artistic past.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

A Montreal deli that was so beloved that it was allowed to circumvent their laws of language.

Every equinox this Maya pyramid puts on a spooky ancient light show.

A flooded Mexican cave that hides a river beneath the water.

These azure waters were thought to lead to the Mayan Underworld.

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

France's most famous cemetery, with some of its most curious tombs.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

A circus legend leaves an unexpected endowment.