from Wikipedia Meshed:
Mashhad (Persian: مشهد, literally the place of martyrdom) is the second largest city in Iran and one of the holiest cities in the Shia world. It is located 850 kilometers (500 miles) east of Tehran, at the center of the Razavi Khorasan Province close to the borders of Afghanistan and Turkmenistan. Its population is 2,868,350 people (2006).
Now Mashhad is notably known as the resting place of the Imam Reza (Ali ibn Musa al-Rida). A shrine was later built there to commemorate the Imam, which in turn gave rise to increasing demographical development.