Mashhad is the centre of Khorasan province, In the ancient times Mashhad was a part of tous,which is now a suburb of Mashhad.
Mashhad population is about 2,300,000 .Holey shrine of Imam Reza,eight imam of the Shiite Muslims is in Mashhad.Imam reza passed away in 818 A.D.
The Shiite Muslims believe that he was poisoned and martyred on the order of Abbasi Caliph therefore his martyrdom venue was called Mashhad(place of martyrdom)
In 203/818, or as some people believe, in 202/817 Imām Rid,ā(A.S.) was martyred in Tūs. His sacred body was buried near Hāroon’s tomb in the garden of H,amīd Ibn Gah,t,abah. The first Shrine was the same one that belonged to Hāroon al-Rashīd, over which in later times a new Shrine was built and its name was changed from Tūs to Mashhad al-Rid,ā. In the year of 400H. a new Shrine and a minaret were added to it.