Mashhad (population: 2,463,393)

Mashhad (also spelt Mashad, literally "The place of martyrdom"), is located 850 kilometers (500 miles) east of Tehran, Iran (Persia), and is one of the holiest Shi'a cities in the world. It is the second largest city with a population of 2.8 million at the center of the province of Razavi Khorasan.