The old part of Bam was one of the world's most spectacular and best-preserved deserted medieval cities.

In architectural and archaeological terms, the ancient Middle Eastern palace city was of major international importance. Surrounded by a magnificent 16th-century city wall, and entered into through complex gateways, the old town has long been famous in Iran for its vast urban landscape of abandoned houses, shops and mosques.

At the heart of the medieval city, inner ramparts enclosed the spectacular palace citadel. It lies on the Old Silk Road, the ancient trading route that connected East Asia to Europe by camel caravans, and flourished as a trading centre and pilgrimage site.

Bam was founded more than 1,500 years ago, and in pre-Islamic times was a centre for the ancient Persian religion of Zoroastrianism. However, many of Bam's old buildings actually date from somewhat later - the 16th and 17th centuries. The thousands of deserted buildings in the old city (which once covered 6 sq km and had a population of up to 13,000) are all made of mud-brick, clay and palm tree timber.

The new town - adjacent to the old one - is densely inhabited and was constructed in the 19th and 20th centuries after its predecessor had been attacked by Afghan and other invaders in the 18th and early 19th centuries.

The deserted parts of the old city were regarded by archaeologists and architectural historians as one of the most complete surviving records of a medieval/early modern urban environment anywhere in the world.

It was used as an army barracks until 1932, after which it was abandoned.