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.

This red light district plaza memorializes the Fab Four and their historic connection to the area.

Model Trains and Much More in Hamburg.

A tilted half-timbered house from 1672 is built into a salvaged segment of a medieval wall.

The small alleys in Lübeck's Old Town are a result of medieval urban sprawl.

You've probably seen these distinctive orange-tiled columns on the big screen.

Berlin's old airport.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

A mammoth WWII anti-air defense tower has been repurposed as a hotel with a rooftop garden.

This contentious squat has stood through fire, violence, and government intervention as a hotbed of leftist protest.

Hamburg's first legal sex work is relegated to a gated street that still does not allow pedestrian women.

Hamburgers are intensely proud of their tunnel beneath the river.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

The bells remain in a shattered heap exactly as they fell when the church was bombed in World War II.

Dancing skeletal figures pay homage to a medieval mural destroyed during World War II.

A statue honors the local legend that the devil helped build St. Mary's church after being tricked into thinking it was going to be a wine bar.

A stunning two-story timepiece within a medieval Brick Gothic church.

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

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

The world's northernmost aquarium looks like it has fallen over.

This functioning parish church is also the site of many concert performances due to its wonderful acoustics.

A small window on Via Piella offers a lovely and rare peek at Bologna's lost canals.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.