Millions of Shias, packed the city of Karbala on Thursday for the culmination of one of the world's largest religious events. The faithful have for days been streaming through the golden-domed mausoleum of Hazrat Imam Hussain (RA), the Prophet Muhammad's (PBUH) grandson who was killed in 680 AD by the armies of Yazid, despite the threat of militant attacks. Many in the sea of black-clad devotees swarming the shrine walked days to reach Karbala, sometimes from cities as far afield as Basra, about 500 kilometres away by road.

Thousands of “mawakeb”, spots where tents are erected by volunteers, are set up along the way to serve the pilgrims food and beverages. Baghdad and much of the country south of the capital come to a standstill in the days preceding Arbaeen, as several major motorways are reserved for pilgrims on foot on one side and authorised vehicles on the other. Over 20 million pilgrims, among them five million Arabs and foreigners, took part in the pilgrimage this year.