The key part of the annual Haj pilgrimage to Mecca has begun. The Eid al-Adha is a three-day festival which commemorates Abraham’s willingness to obey God by sacrificing his son.His obedience is re-enacted by the sacrificing of sheep. Another important ritual is the throwing of stones at pillars where Islam says the devil appeared to Abraham. The Masjid al-Haram, or Grand Mosque, is the focal point of the rites observed during the Haj. In the middle of the structure is the Ka’aba, the stone building which is a symbol of unity for all Muslims as all prayers are directed towards it. This year’s pilgrimage has been touched by tragedy, like previous ones. The collapse of a hostel killed at least 76 people. Stampedes have left hundreds of pilgrims dead in the past. Security is high amid fears of terrorist attacks against the US-allied Saudi authorities, and there are also worries about the spread of the human form of bird flu.