This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

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

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

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.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

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

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

London's smallest police station is barely the size of a phone booth.

Europe's largest collection of matchbox designs is a fascinating exploration of the cultural history of the world.

This giant sculpture made of trash is a critique of society's wastefulness.

Elaborate tile work in this railway station tells the story of Portugal.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

A hidden three-foot-wide house separates these two regal churches.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

A working steam clock, one of only a few in the world, located in Vancouver's Victorian Gastown.