Burial site of a Jewish prophet revered in Iran.

This lake in northwest Iran has started turning from green to red more frequently than scientists are comfortable with.

The tower in this 1,000-year-old mud-brick village seems to vibrate for no apparent reason.

This ancient fortress in Iran was once the oldest and largest treasury in the world.

Hundreds of stones dangle from barren trees in the middle of the desert.

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

The colorful soil of Iran’s "Rainbow Island" attracts artists and nature lovers.

One of the largest and oldest caravansaries in Persia.

The hottest, driest, and most scenic desert on Earth.

These little castles each held thousands of pigeons.

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

Hydraulic systems in an ancient underground Iranian city.

One of the world's largest salt caves is filled with fragile salt sculptures, salt rivers, and huge salt megadomes.

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

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

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

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

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.

Controversially restored in the 1970s, this giant 15th-century mosque is shrouded in legend.

Home to what was once considered the largest gate in central Asia.

These "50 Fortresses" have been unearthed in the ancient oasis of Khwarezm.