The mysterious empty cupola behind the monumental arch points to an ancient prophecy of Delhi.

A startling, centuries-old subterranean marvel hides in plain sight.

A mysterious architectural gem in one of the most elegant areas of Buenos Aires.

One of the two original gateways into the Kasbah, this gateway is a nesting site for storks.

One of the tallest waterfalls in Africa is also home to a population of monkeys who enjoy the waters and the occasional guest.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

Traditional 11th-century outdoor tannery.

This amazing oasis of art and plants is hidden on the outskirts of Marrakesh.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

Deliberately hidden for centuries, the magnificent Saadian Tombs were eventually uncovered in 1917.

The other side is actually green.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

Founded as a refugee camp, now a popular tourist spot.

Perhaps the most spectacular grotto along the Algarve coastline.

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

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

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

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

An unassuming music museum recounts the rags to riches story of a dramatic Portuguese genre.

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

The world's largest wooden structure.