Mecca is the only pilgrimage site officially accepted by all Muslims, but Iran and Iraq are home to a number of sites considered holy to the Shia faithful: Hussein was buried at Karbala, for example, and the tomb of Ali is in nearby Najaf. Both of these Iraqi cities have become pilgrimage sites for the Shia faithful, secondary for them in importance only to Mecca. The primary centers of Shia learning — Najaf (in Iraq) and Qom (in Iran) — are also shared between the two countries. Because of this relationship, the countries share a centuries-long history of intellectual exchange, as Shia scholars and clerics from both Iraq and Iran moved between schools and visited the one another�s pilgrimage sites.

After the 1979 Islamic Revolution, the Iranian government sought actively to export its ideas, and the secular (though nominally Sunni) Iraqi government feared that its Shia majority would heed the call and revolt themselves. This led to increased oppression of the Iraqi Shia population and was one of the causes of the Iran-Iraq conflict. Saddam Hussein’s fears proved groundless, however, as nationalism trumped any pan-Shia feeling on both sides, and Shia troops fought one another throughout the war.

After the fall of Saddam Hussein’s Sunni government in 2003, the country’s Shia majority rose to power, forming the first Shia government there in several centuries. Many of the Shia parties that currently dominate Iraq’s parliament have close connections to the Iranian government. These ties are a source of concern not only to Sunni Iraqis but also to many of the Sunni governments in the area, who fear Iranian dominance — a fear that has been compounded by Iran’s recent push for nuclear power. As of early 2007, sectarian violence between Iraqi Shia and Sunni militias continues unabated, with both sides benefiting from an influx of resources and manpower from outside supporters.

Mashhad
The eighth Imam, Reza, is buried in Mashhad, and his golden-domed tomb is the most important Shia pilgrimage site located in Iran itself, visited by hundreds of thousands of pilgrims annually. The city itself is laid out in a circle around the shrine, and the region surrounding the tomb serves as “bast” or a place of refuge; the shrine itself has statelike authority, and can grant asylum to those who seek safety.

Qom
Qom is the center of Shia scholarship in Iran, home to the country’s most important madrassas; the tomb of the sister of the eighth Imam makes the city an important Shia pilgrimage center as well. Khomeini trained here as a student, and returned here in 1979, making it a base for the Revolution. It continues to be a center for Shia scholarship.

Shiraz
The city of Shiraz is an important pilgrimage site — though not for its Shia heritage. Historically, Shiraz has been a center for Iran’s Sufi intellectuals. Sufism is a mystical movement that first emerged in Shia communities during the 8th century (though there are Sufi groups in Sunni Islam as well). While an incredibly wide variety of beliefs and practices exist among the Sufi brotherhoods, Sufis in general reject the literalism of traditional Islamic jurisprudence in pursuit of a personal — and often mystical or ecstatic — relationship with God.

Many of the Islamic world’s greatest writers and thinkers — including Hafiz, the Persian language’s greatest lyric poet — were attracted to Sufism, joining the Sufi brotherhoods. Hafiz is buried in Shiraz, and his tomb has become a destination not just for Sufi adherents, but for Iranians in general, who consult his collected poems as an oracle. It is believed that if one keeps a question in mind and chooses at random one of Hafiz’s poems, the first couplet will provide an answer.

Najaf
Najaf is the site of the tomb of Ali, Muhammad’s son-in-law, the Fourth Caliph and First Imam, and like Qom it is a center of Shia scholarship. The Shrine of Ali is one of Shia Islam’s holiest places, and the city that grew up around it has remained a center of Shia thought, even under Sunni and secular governments. Khomeini moved to Najaf in 1965, after being sent into exile by the Shah, and spent thirteen years there, during which time he formulated much of the political theory he was to put into practice following the 1979 Revolution. Najaf has never been an easy city to govern — its residents revolted against both the Ottomans and Saddam Hussein — Najaf has also served as the base for radical Shia leader Moqtada al-Sadr’s Mahdi militia fighting the postwar Iraqi government and the U.S. Army. On January 20th of 2007, gunmen abducted and later killed five U.S. servicemen.

Karbala
Husayn, Ali’s son, Muhammad’s grandson, and the central martyr in the Shia tradition, died at Karbala and is buried there. For the Shia, his tomb is the holiest site outside of Mecca and Medina, and many make the pilgrimage there — up to a million pilgrims visit the city to observe Ashura, the anniversary of Husayn’s death. Like Najaf the city has become home to a number of Shia madrassas, or Islamic religious schools.

At Ashura, Karbala is the site of the “ta’ziya,” a passion play that reenacts the circumstances leading up to the martyrdom. The ritual is practiced elsewhere, but the observance is particularly intense in Iraq in general and at Karbala in particular, including a bloody self-flagellation ritual — in which young men not only whip themselves, but cut their scalps with swords — rarely practiced elsewhere in the Islamic world.

Baghdad (Kazimayn)
The shrines to Musa al-Kazim and Muhammad al-Jawwad, the 7th and 9th Imams, are located in Kazimayn, now a Baghdad suburb. Baghdad itself served as the capital of the Sunni Caliphate on several occasions from the 8th through the 13th centuries; it was only part of a Shia state for the first few decades of the 16th century, when it came under Safavid rule.

Samarra
Samarra is the site of the shrines to the 10th and 11th Imams, Ali al-Hadi and Hassan al-Askari, though more interestingly the city is also the place from which the 12th “Hidden” Imam, Muhammad al-Mahdi, is believed to have entered his period of occultation. There is a shrine built atop the cellar in which the child Imam was last reported seen. In 2006 the golden dome of the Al Askari mosque was bombed and sustained massive damage. Many analysts describe the bombing as the beginning of a sectarian civil war in Iraq.

Mecca
Pilgrimage to Mecca is compulsory, at least once in a lifetime, for all Muslims who can possibly afford it. The “hajj” (pilgrimage) itself centers on the Great Mosque surrounding the Kaaba, the cubical structure thought to have been built by Abraham and Ishmael — the shrine that the world’s Muslim’s face in prayer everyday.

The hajj is tightly regulated by the Saudi Arabian government, which limits the number of visitors (generally to two million) for the annual observance, and forbids political activity or sloganeering during the pilgrimage. Following the 1979 Islamic Revolution, however, Iranian Shia pilgrims challenged this authority, waving portraits of Khomeini and openly chanting anti-Israeli and anti-U.S. slogans along the route and at the Kaaba itself; tensions came to a head in 1987 when 400 pilgrims were killed in fighting between Iranian demonstrators and Saudi police. The Iranian protests were widely seen — as was the 1989 fatwa against Salman Rushdie — as challenges to Sunni dominance. Since the 1990s, relations have improved, especially following Iraq’s invasion of Kuwait, and the hajj has been peaceful since.

Medina
While Medina is an important, if optional, stop for pilgrims on the hajj, it is a pilgrimage destination for the Shia. The shrines to the 2nd and 4th Imams, Hasan and Ali Zayn al-Abidin, are located there; Muhammad’s daughter Fatima is also buried in Medina.