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

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

On this tiny spot of land in the middle of Lake Titicaca the only ones who do the knitting are the men.

The Uros people live on floating reed islands in lake Titicaca.

This stone complex marks the urban center of a lost civilization.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

An Inca spa, military outpost or maybe… both?

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

One of Ireland's most infamous prisons for rebels including men, women and children.

The modern birthplace of Irish freedom.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

This massive library holds what was once the largest book collection in the world.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

A 1950s Googie burger stand is now a Los Angeles landmark.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

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