Mecca

Algerian Muslim pilgrims take pictures on a rocky hill called the Mountain of Mercy, on the Plain of Arafat near the holy city of Mecca, Saudi Arabia, Monday, Oct. 14, 2013. The hajj, a central pillar of Islam and one that able-bodied Muslims must make once in their lives, is a four-day spiritual cleansing based on centuries of interpretation of the traditions of Prophet Muhammad. (AP Photo/Amr Nabil)

Amr Nabil/AP

Algerian Muslim pilgrims in Mecca for the hajj take pictures on the Mountain of Mercy, near the Saudi Arabian holy city. The hajj, a central pillar of Islam and one that able-bodied Muslims must make once in their lives, is a four-day spiritual cleansing based on centuries of interpretation of the traditions of Prophet Muhammad. Read more

A Muslim pilgrim prays atop Mount Mercy on the plains of Arafat during the peak of the annual haj pilgrimage, near the holy city of Mecca early morning October 14, 2013.  An estimated two million Muslims were in Mecca, Saudi Arabia, on Monday morning for the start of the annual Haj pilgrimage.

Ibraheem Abu Mustafa/Reuters

A Muslim pilgrim prays atop Mount Mercy on the plains of Arafat during the peak of the annual Haj pilgrimage, near the holy city of Mecca early on Monday morning. An estimated 2m Muslims were in Mecca, Saudi Arabia, for the start of the annual Haj pilgrimage.

A Muslim pilgrim prays at Mount Al-Noor ahead of the annual haj pilgrimage in Mecca October 10, 2013. Mount Al-Noor houses Ghar-E-Hira or Hira cave, where Prophet Mohammad is said to have spent a great deal of time in the cave meditating and it is believed that he had received his first revelation inside this cave.

Ibraheem Abu Mustafa/Reuters

A Muslim pilgrim prays at Mount al-Noor ahead of the annual Hajj pilgrimage to Mecca on Thursday