The historic tower houses of this nearly abandoned Greek town have been compared to the spikes on an iguana's back.

An ancient octagonal weather station named for the eight Greek gods of wind.

The ruins of an abandoned medieval city where the last Byzantine emperor was crowned.

This town named for the ancient God of War is home to fewer than a thousand people, but it's the birthplace of the Greek Revolution.

This 15th-century island fortress later served as home to the executioners no one wanted to live near.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

This legendary city has been a tourist attraction for centuries.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

The hallucinogenic center of the ancient world.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The final resting place of the great navigator, or maybe his brother.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

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

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

2300-year-old Roman road connecting the empire.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

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

A cluttered and astounding collection of antiquities and curiosities.

One of the highest Roman forts in Britain is set amid dramatic scenery on a notoriously difficult road.