Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

A beer pipeline runs beneath Bruges.

Portugal's National Pantheon has a history of curses, collapses and financial problems.

A stairway to heaven, or to nowhere at all.

This wooden hotel is a temple to German sustainability and forest conservation.

Dine at a legendary after-hours joint frequented by David Bowie and Iggy Pop.

The original burial place of this preeminent 18th-century Jewish philosopher was razed by the Nazis.

This TV tower once secretly housed a GDR intelligence team.

The site of good faith and good nature in the fictional world of Kcymaerxthaere.

A museum in the building where Nazi Germany signed its surrender tells the story of World War II from the Soviet perspective.

A monument to the man who almost killed Hitler.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

Skeletons, medical artifacts, and other obscure and precious treasures all displayed in a wooden pharmacist's cabinet.

A unrivaled and rather horrifying collection of wax dermatological models.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

Indents in the pavement are all that remain from a grisly death machine in Paris.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

This enormous 32-foot painting depicts Poland's greatest medieval battle in glorious detail.