Among other important regions, mention must be made of Fars and Khorasan. Fars is the mountainous region of south-central Iran and is in many ways the historical and cultural heartland of Iran. One of the earliest advanced civilizations in Iran began there, two great Iranian empires originated there, several of Iran’s most famous archaeological and artistic sites are located there, and many of Iran’s greatest writers and poets lived there. The capital, Shiraz, is among the most attractive cities in Iran, a place whose reputation conjures up the images of roses, nightingales, gardens, ambrosial wine, heavenly poetry, and relaxed living that seem so quintessentially (or stereotypically) Iranian. It is not without reason that among foreigners, since the time of the ancient Greeks, the name of this region, Persia, has been applied to the whole of Iran. If Fars is the heartland of Iran, Khorasan is its shield, its main frontier province. The mountains of northeastern Iran do not pose quite the barrier to movement as do those of the north and west. While Iran has occasionally been invaded from the west, it has been under an almost constant threat of attack or invasion by the nomads of central Asia. The fortified villages and garrison cities of Khorâsân have had the historical task of resisting that pressure and have suffered the most from failures to do so. Today, the Iranian province of Khorasan is only a remnant of what was once a much larger territory and an important bastion of Iranian culture. On the other hand, now that the external threat has ebbed, the economy of the area is reviving, and its population is increasing at a faster rate than that of other parts of Iran. Its major city, Mashhad, now has over 2 million inhabitants (up from 240,000 in 1956). Mashhad is also a spiritual center of Iran, since one of the most important religious shrines is located there and is visited by about 12 million pilgrims each year.