A series of waterfalls so massive they straddle the border of Argentina and Brazil.

The largest falcon hospital in the world, caring for over 6,000 feathered patients every year.

Whitewashed mosque contains the world's largest carpet.

The ancient latrines of the Greeks, in all their public glory.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

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

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

This seemingly random 30-foot statue of an oryx in Qatar's capital was a mascot for the 2006 Asian Games.

This remote British Imperial telegraph relay outpost drove men insane.

Nature's water park in the Wadi Bani Awf valley is full of pools flanked with cliffs and natural water slides.

This bazaar is one of the oldest in the Arabian world.

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

Groups of prehistoric tombs that dot the mountains of northern Oman.

An imposing Omani fortress surrounded by date palm trees.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

Marked by the hand of the explorer Henry Morton Stanley.

Named after a legendary garden called Eram in southern Arabia, built by order of Shaddad, an Arab king who wanted to compete with Paradise.

This ancient burial site is believed to be one of the first earthquake-protected structures in the world.

Ancient structures used to make and preserve ice in the deserts of Persia.

17th century mosque for Shah Abbas' harem.