Half-hidden by grassy slopes, this striking Spanish colonial fort is now a museum of underwater archaeology.

One of the few places where you can visit a cenote and Maya ruins at the same time.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

The towering Pinocchio stands 63 feet tall in the Italian village his creator frequented as a child.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Tourists to the mountaintop Sicilian town often overlook its ancient fortifications.

This triumphal 16th-century arched gateway leads to the oldest street in Palermo.

The remains of an ancient Roman city are hidden underneath Bologna's beautiful public library.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

Psychoanalyst Carl Jung reported a paranormal experience after visiting this mosaic-lined Roman baptistry.

An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.

The Renaissance-era courthouse is a relic from the fortified town's centuries of Venetian rule.

'The Letters of Utrecht' lays out a ribbon of poetry one letter at a time, with no final verse in sight.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

In the Netherlands, one of the world's largest private car collections can be found.

This neighborhood of futuristic ball houses looks like an alien settlement in a science fiction film.

This memorial museum chronicles the apocalyptic destruction of the First World War.

The Slovenian architect designed many landmarks in the capital city, including his own dream house.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

This one-time health resort was used by aristocrats around the world.