This beautifully restored fortification kept the city safe for centuries.

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

This living legend of maritime history is enjoying a second life.

No building in the world leans as far as the so-called “Leaning Tower of Abu Dhabi.”

Whitewashed mosque contains the world's largest carpet.

As the Dead Sea continues to deplete, massive sinkholes open along its banks.

A section of the long chain that blocked enemy ships from entering Constantinople.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

A marvel of Byzantine engineering under the streets of Istanbul.

Ancient serpentine sacrifice holder that has stood the test of time.

A fountain standing as a testament to a doomed alliance.

A sixth-century Byzantine cistern hidden below a modern carpet store.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Over the centuries, this island paradise has done it all, from providing monks with ecclesiastical respite to sheltering an exiled Leon Trotsky.

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

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

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

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

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.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Constructed along the shores of Lake Zurich, this pavilion is a walk-through work of art.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.