One of the Shiite sect’s most important religious cities in southern Iraq, Karbala contains the shrines of Imam Hussein and his brother Abbas, the two sons of Imam Ali Ibn Abi Talib, and Shiite Muslims from all over the world pilgrimage to them with an annual visit known as the Arbaeen visit, with their numbers reaching millions in one of the most important and prominent religious carnivals. It also contains a number of historical sites, such as the Al-Ukhaydir fortress.