Hidden in the garden of physicist Erwin Schrödinger's house is a life-size figure of a cat from his famous thought experiment.

A 200-year-old tavern challenges guests to finish a glass of wine while hanging from a ceiling beam.

This massive boulder was hurled into a Zurich church when a gunpowder depot was struck by lightning in 1652.

The oldest skyscraper of Europe now stands dwarfed by the surrounding structures.

An ancient Egyptian temple sits within a modern European museum.

The remains of a medieval wall discovered in the basement of a jewelry store.

The location of the world's first telescope demonstration.

A giant yellow phallus sculpture hidden in the gardens of the Museum Boijmans Van Beuningen.

An art installation memorializing a tram stop, which became a tram stop.

The site of the original experiment that would be used to disprove the theory of luminiferous ether.

There are hidden patterns on the subway seats of some Stockholm metro cars.

Krakow's own version of the Hollywood Walk of Fame.

Remnants from a time before electricity.

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

Where visitors can play more than 150 retro arcade games.

A Soviet era flat that refused to conform to the dull gray standards.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

An underground city of salt.

This grubby wall is said to be one of the Earth's esoteric energy centers.

The oldest wind turbine in Europe, constructed by a group of friends in 1932.

Brought to you by the makers of fiberglass dinosaurs.

A large boar commemorates the city's founding and the origin of its name.

A small square populated with giant birchwood sculptures.