Millions of Shia pilgrims converged on the holy city of Kerbala for the Arbaeen religious commemoration on Tuesday, the largest annual gathering of people anywhere on earth. Walking in long columns stretching back unbroken for as much as 50 miles, sleeping and eating in tents erected by supporters beside the road, the event has become an overwhelmingly powerful display of Shia belief and solidarity. The Arbaeen Pilgrimage is the world's largest public gathering that is held every year in Karbala, Iraq at the end of the 40-day mourning period following Ashura, the religious ritual for the commemoration of martyrdom of the grandson of Prophet Mohammad and the Third Shia Imam, Hossein ibn Ali's in 680.
