A Nesting Doll of Churches.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Jesus' footprints and the first catacombs in the world.

2300-year-old Roman road connecting the empire.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Ancient snack bar of the Roman Empire re-opened.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

Fortified medieval tower house with lovely roof garden.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The fairy tale castle of the "fairy-tale king."

Every hour the doors open to reenact the legend of the heroic mayor who saved his town by drinking a gallon of wine.

Horrifically creative torture devices and shame punishments line the walls of this chilling museum.

The telescope that discovered Neptune.

Go surfing on this urban wave, "hacked" by local surfers.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.