Rome's semi-secret peephole vista is also a former Crusader stronghold.

Hidden in the hills of Western Pennsylvania lies one of the best-kept ghost towns in America that you can legally visit.

The oldest residential street in Europe also features an optical illusion.

A train car sitting on a rooftop makes an unlikely and picturesque setting for dinner.

The watery grave of an impractical idea.

Owned by Native American women, this brewery is a celebration of indigenous culture in the American Southwest.

Once a safe haven for locals engaged in blood feuds, this 400-year-old fortified tower is now a museum showing what life was like for those lying in wait within its walls.

Luminaries of all stripes have sipped strong Greek coffee at this cafe since 1839.

Loyal fans of one television's most famous painters still come to pay their respects.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

A mysterious monument where a woman who records say never existed was burnt alive for being a witch.

This innocent-looking townhome is actually a subway exit.

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

A short tunnel built straight through a magmatic dike.

You can find America's highest suspension footbridge at Grandfather Mountain in North Carolina.

The "Bridge Over the Atlantic" lets you cross the waterway in mere seconds.

A 25,000-square-foot display with dozens of model trains in intricate miniature worlds.

Heralded as the oldest statue in London.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

The Kalamazoo factory has 100 years of instrument-making, and one big wartime secret.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

Tracing a path of more than four miles around a frozen lake, this is the longest skate trail in the United States.

This amazing abuela became a diehard metal fan late in life and an icon of Madrid's '80s rock scene.

Once the center of power for the region's various factories.