A floating cat sanctuary on an Amsterdam canal.

Amsterdam's narrowest house facade is a monument to 17th-century tax evasion.

This unattributed sculpture in Amsterdam is hiding in plain sight.

This cheese shop also houses a museum devoted to Dutch dairy.

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

The compass on its front was a handy tool for 17th-century merchants who needed to know the direction of the wind.

Christ's blood preserved in a Belgian town.

Climb inside an iron crystal magnified 165 billion times its normal size.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

When you're a great Russian Tsar, even your vomit gets a statue.

Brussels' favorite peeing boy has a sister.

A little sculpture with a large wardrobe.

The oldest stone house in Paris was built by its most famous alchemist.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

The celebrated eyesore created by starry-eyed sweethearts.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

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

This magenta statue commemorates the legendary marriage between a mermaid and the city's founder.

Statues of a fire-breather, a clown, and a whole performing troupe celebrate Luxembourg's creative side.

Some believe that the artist behind this whimsical statue inserted his own likeness as a way to discreetly flip the bird.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

Paris' linguistic guide to the international language of, yes, love.