One of the most beautiful Persian carpets is the Kashan. It comes from the Iranian city of the same name, where local artists have been hand-weaving it from wool or silk since the 16th century. One in three Kashan residents is employed in the production of local carpets, with mothers passing on the skills of tying to their daughters, while fathers teach their sons to shear sheep and dye wool, devise designs or set looms. A seasoned expert will know a kashan at a glance, as these are very popular and celebrated carpets that are exported from the hot city on the edge of the salt lake and desert all over the world. In 1973, carpets were also produced by machine in Kashan, and a few years ago the entire local industry of Persian Kashan carpet production was listed by UNESCO as one of the treasures of the inviolable cultural heritage of mankind. The rarest type of Kashan is considered to be the mochtasham, with delicate patterns of flowers or leaves on an ivory or gold background; such specimens are valued by collectors at hundreds of thousands of crowns. For many, it is the traditional Kashan carpet with a central medallion on a red field that comes to mind when they think of a Persian rug.