Mashhad, capital of Iran's Khorasan Province and Iran's second largest city, is known for the shrine of Imam Reza (A.S), the Eighth Imam of the Shia Muslims who follow Twelve Imams. Mashhad literally means "burial place of the martyr." The city started out as Sanabad, a stop-over for trade caravans traveling to and from Turkmenistan. It was only after the martyrdom of Imam Reza (A.S) at Tus in 818 and the construction of his shrine here that the city became a pilgrim site. The ruined city of Tus lies about 23 km from Mashhad.
The city of Mashhad has been built around the shrine of Imam Reza (A.S). The holy areas in and around the holy shrine are known as Bast. The Bast forms a perfect circle and there is one circular road around it and four roads between the Bast and the rest of the city. The layout of the city is unique as these four roads point to the compass points in the north east, north west, south east and south west directions.