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.

Salt cured mummies continue to turn up in this Iranian mine.

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

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

A dreamy mausoleum honors Persia's most famous poet.

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

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

A historic trade hub teeming with gorgeous architecture, colorful goods, and vibrant designs.

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

One of the largest and oldest caravansaries in Persia.

These little castles each held thousands of pigeons.

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

This vast, water-filled underground labyrinth can only be toured by boat.

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

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.

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

Hydraulic systems in an ancient underground Iranian city.

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

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.