AP PHOTOS: Millions of Muslims embark on the annual Hajj pilgrimage to Mecca

The annual Islamic pilgrimage to Mecca in Saudi Arabia has begun. It’s required once in a lifetime by every Muslim who can afford it and is physically able to make it. The Hajj, one of the Five Pillars of Islam, occurs once a year during the lunar month of Dhul-Hijja, the 12th and final month of the Islamic calendar year.