Yazd Water Museum

For at least 2000 years Iranians have been digging qanats (underground water channels) to irrigate crops and supply drinking water. To build a qanat you first need to find an underground water source. This source could be more than 100m deep, but as the whole system is reliant on gravity the source must be higher than the final destination. Then you dig a tunnel just wide and tall enough to crawl along, so the water can flow across an extremely shallow gradient to its destination.

The mounds of soil you'll see in long lines across the desert are the top of wells, dug to dispose of excavated soil and allow ventilation.

Because of the hazards and expense of constructing a qanat, complex laws govern every aspect of their use and maintenance. Iran is thought to have more than 50,000 qanats. While modern irrigation projects now take priority, qanats and other traditional methods of supplying water are still very important. And as hundreds of towns and villages - including Bam, Kashan and Mahan - still rely on qanats for water, the highly skilled and well-paid qanat builders of Yazd won't be picking up redundancy cheques for many years yet.

For the lowdown on qanats, head for the impressive Yazd Water Museum , located in a restored mansion that happens to have a qanat or two underneath. The displays are clear and mostly in English.