Mashad is the holiest city in Iran where Imam Reza, the agreeable one, the great grandson of Muhammad, is buried. It is also the source of Turquoise and most of the finest spices in Iran. The best saffron and the finest berberis berries come from Mashad. In ancient times it was known as Toos and is close to Nishapur, birthplace of Omar Khayyam and Attar Al-Din.