Those taking the Arbaeen pilgrimage from different parts of Iraq gather at the holy mausoleum to mourn the martyrdom of the third Shia Imam (AS) and his companions in the 680 AD Battle of Karbala.
Arbaeen falls on Thursday, October 8, this year.
Arbaeen, which is one of the largest religious gatherings in the world, comes 40 days after Ashura, the martyrdom anniversary of Imam Hussein (AS).
Each year, a huge crowd of Shias flock to the Iraqi city of Karbala to perform mourning rites.