A nearly 25-foot concrete sculpture of Sylvette, Picasso's muse.

This charming pup is meant to celebrate the youth and stubbornness of the city's students.

For over 100 years the most important physicists in the world have autographed this university wall.

An early 19th-century English style garden hidden in the Rotterdam cityscape.

Four giant movable street lights decorate this modern Rotterdam square.

A concrete Picasso in the middle of a student housing complex on the outskirts of Stockholm.

Rotterdammers' dirty minds gave this Santa a dirty nickname and cursed it to a life of wandering.

A scale model of the world's largest existing lensed telescope.

This public toilet built in the famous Amsterdam School architectural style is a Dutch national monument.

It's forbidden to dig within this ancient Roman fort hidden beneath a playground.

A strangely curved lamppost stands tall over this avenue in Rotterdam.

A former suicide bridge is now accumulating symbols of love instead of a body count.

This century-old street sign is a forgotten remnant of the old city.

A dramatic art installation features a BMW flying out of a building in Rotterdam.

Science meets wall art to highlight the beauty of famous mathematical equations.

A true Valhalla for cactus and succulent lovers.

A relic of the old jail still stands in its original location.

The last of Amsterdam's original sea level markers remaining in place.

This unattributed sculpture in Amsterdam is hiding in plain sight.

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

A floating cat sanctuary on an Amsterdam canal.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

A beautifully eclectic mix of architectural styles.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.