The 20-mile causeway that separates the Netherlands from the sea.

A trio of red, white, and blue stones embedded in the streets of Leiden are markers of medieval territory and law.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

Fortified medieval tower house with lovely roof garden.

The first botanical garden, a feather in the cap of the Grand Duke of Tuscany.

This deceiving white sand beach gets its brilliant hue from the chemical discharge of a nearby factory.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

This giant radio telescope would be a rusting ruin if it hadn't become such a beloved relic.

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

A historic observatory now an astronomy museum beautifully situated at the moat of the Middle Age city centre.

No one knows the meaning behind this giant sculpture of a nude woman with a fork riding a rooster in Havana.

This imposing memorial contains the remains of Che Guevara — and 29 other guerrillas who died with him in Bolivia.

In terms of history and architecture, this is one of the most remarkable cemeteries in the world.

His music once banned in Communist Cuba, John Lennon is now immortalized in bronze by Castro, who considers Lennon a "fellow dreamer."

Neo-cave art on the macro scale.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

This Netherlands museum holds a gloriously mechanical collection of ornate musical automata.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

Birthplace of the "Cat in the Cradle" and a cluster of iconic, original windmills that let the Dutch tame the seas.

Go inside a revolutionary, cage-less zoo where 35 species live and some of them roam free alongside their human visitors.

The tallest waterfall in the Netherlands is a lovely, stepped feature that is only 50 feet tall.

This artificial ring island was built to hold cubic tons of polluted dirt.

This insurance company building reminds customers that witches, bears, and gnomes are out there, best be insured.