These little castles each held thousands of pigeons.

One of the largest and oldest caravansaries in Persia.

The fire inside this temple has burned for more than 1,500 years.

The ancient necropolis houses the immense rock-cut tombs of four Persian kings.

Modern-day cave dwellers carve elaborate homes out of volcanic debris.

This beautiful system of tunnels built into natural rock serves as a centuries old plumbing system.

A sophisticated astronomical tower built by one of the greatest Persian scholars of the Islamic Golden Age.

The vertical-axis windmills of ancient Persia have been grinding flour for 1,000 years and counting.

Putrefaction plateaus in Iran, where the dead were sent for decontamination before going to their final resting place.

A 1,500-year-old, 3-story subterranean city where ancient Persians took refuge in times of war.

This ruined fortress was the stronghold for a persecuted medieval leader and his infamous Assassins.

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

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

The palace of the King of Kings, burned by Alexander the Great.

Iran's colorful terraces are a rare geological masterpiece.

Mirrors and glass shards cover every inch of this arrestingly beautiful mosque.

Ghost Town in the Demilitarized Zone of the Golan Heights.

This sixth-century synagogue was first reconstructed digitally, then in real life.

A Biblically notable site over the ruins of an ancient city that is now a protected World Heritage site.

Tens of thousands of rocks make up what is thought to be a giant star calendar.

Named for the biblical warrior, the largest castle in Israel actually dates to the Middle Ages.

This beautifully historic Bahrain fortress might not be the most popular attraction around, but that might make it all the better.

This archaeological site boasts temple ruins that date back 5,000 years to the Dilmun culture, and may have been described in the tale of Gilgamesh's search for immortality.

This centuries-old tree tells an unusual tale of vegetation and fertility in the desert.