The world's first clock to use set theory as a measure of time required the invention of a new light bulb just to maintain its obtuse measurements.

An astonishingly accurate water clock that doubles as an hourly spectacle in this Berlin shopping area.

A thin golden line commemorates the deadliest terrorist attack in recent German history.

A hidden art gallery in an abandoned Warsaw fort.

A group of tiny bears has occupied various spots across Warsaw's Bemowo district.

These plaques found across Warsaw commemorate the sites where executions or battles took place during the German occupation.

A heavily politicized roundabout discussing the state of a heavily politicized country.

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

A statue honors the children who fought Nazis in Poland.

This bell stars in a tragic love tale and is said to make wishes come true.

Catch a scenic view of Warsaw's Old Town from the top of a centuries-old dumping ground.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

Legend says this is actually a heartbroken prince waiting for his true love's kiss.

The last king of Poland was interred in this church nearly 200 years after his death.

After the famous composer died in Paris, his sister snuck his heart out of the country to honor his wish that it be buried in their native country.

Hundreds of notes give thanks to the patron saint of lost causes.

Special benches that play Chopin's music are scattered throughout his native city.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.

One of Warsaw's coolest malls was once a center for anti-Nazi resistance activity.

Atop this library is one of the most beautiful green spaces in Warsaw.

The world’s narrowest house makes for an awkward, four-foot-wide living space.

At night, this memorial illuminates a ghostly outline of a footbridge that connected two sections of the Warsaw Ghetto.

Order “Proletariat’s Cutlet” at this communist-themed restaurant allegedly once visited by Lenin.