This gold-winged spire celebrates the first true flight around the world.

This working class sculpture pounds his hammer all the livelong day.

The first park built over a freeway is a brutalist masterwork.

This former coal gasification plant found a curious second life as a popular public park.

A wall of chewing gum moonlights as collective art.

A museum dedicated to the history and exploration of both popular music and science fiction.

An extraordinarily ornate museum in San Diego holds wondrous anthropological treasures.

A well-worn marker in a forgotten alleyway is all that remains of what had been one of Manhattan's most beautiful buildings.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

A floating cat sanctuary on an Amsterdam canal.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

A beautifully eclectic mix of architectural styles.

The history and future of cannabis.

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

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This unattributed sculpture in Amsterdam is hiding in plain sight.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

The body of at least one victim of a construction accident was left behind in the collapsed pylon, buried under tons of concrete.

The last bastion of Roman presence north of the Alps looms over a German town.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.