The holy shrine of Imam Ali (AS) in the Iraqi city of Najaf, hosts thousands of pilgrims on their route to the holy city of Karbala to attend the Arbaeen procession. Millions of mourners from across the world arrive in Iraq to mark Arbaeen and pay tribute to the third Shia Imam who was martyred along with his 72 companions and family members in the Battle of Karbala in 680 AD.