This stone in Lake Geneva was once the reference point used to determine altitude in Switzerland.

A treasure trove of scientific instruments from the 17th and 18th centuries.

A prime example of socialist modernist architecture, wrapped in a enormous fresco about the media.

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

Switzerland's oldest public observatory is an important part of the Zurich cityscape.

This public observatory is home to the "celestial cannon," the longest pointable telescope in the world.

Where visitors can play more than 150 retro arcade games.

A small square populated with giant birchwood sculptures.

The first successful human heart transplant is depicted through wax figures at the hospital where it the surgery took place.

The grave of the famous painter is marked by a simple stone in the ground.

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

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

A historical observatory still in use by modern astronomers.

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

A town that sets itself apart with supersized designer seating.

Remnants from a time before electricity.

A socialist building dedicated to teachers showcases one of the largest Soviet mosaics in the world.

This bathhouse includes an option to soak in radioactive water.

This pair of unsuspecting buildings are in fact the very first modern skyscrapers in Europe.

The site of Stockholm's last public execution.

A monument to the 16th-century mathemetician who dedicated his life to calculating the numerical value of pi.

A memorial commemorating the place where Truman gave the order to deploy the first nuclear bombs on Japan.

These 250-year-old wagon tracks are a lasting sign of Dutch migrants crossing the mountains.

A statue of an astronomer gazes at the sky as a tribute to Caroline Herschel.