Arbaeen marks the end of a 40-day mourning period for Imam Hussein, a grandson of the Prophet Mohammad and a central figure of Shi'ite Islam who was killed in a seventh century battle. His followers believe he was buried in Karbala.
Pilgrims enter the Imam Abbas shrine as they attend the religious ceremony of Arbaeen, in Karbala, Iraq, January 3, 2013.
Muslim pilgrims mark end of the Arbaeen, which falls 40 days after the Shi'ite holy day of Ashura, Karbala, January 3, 2013.
Pilgrims attend the religious ceremony of Arbaeen, in Karbala, Iraq, January 3, 2013.
Shi'ite Muslim worshippers gather in front of the holy shrine of Imam Abbas, seen in the background, to mark the Muslim festival of Arbaeen in Karbala, Iraq, January 2 , 2013.