The annual haj pilgrimage began in Mecca today when hundreds of thousands of Muslim pilgrims put on white clothes, packed their bags and left for a tented encampment on the edge of the holy city.
In central Mecca, some latecomers performed the ritual walk seven times around the Kaaba, the ancient cubic shrine which all Muslims face when they perform their daily prayers.
More than 1.6 million pilgrims have come to Saudi Arabia from abroad for the haj, the largest regular religious gathering in the world and an obligation which all Muslims should perform at least once if they are able to.
Pilgrims from within Saudi Arabia - Saudis or foreign workers - mean the total often exceeds 2.5 million, posing logistical and health challenges for the authorities.
"We have to raise (health) awareness among pilgrims from some countries," Health Minister Hamad al-Manei told Al-Jazeera, the Arabic broadcaster which has been permitted to cover the rites this year. Al-Jazeera is usually banned.
"Some of the pilgrims coming from outside do not know Arabic. With different languages and peoples coming, of course there are difficulties," the minister said from Mecca.
The government has said it will crack down on pilgrim squatters who cause overcrowding and has taken precautions against bird flu, after recent cases where the deadly H5N1 strain of the virus killed birds in the Riyadh area.
The Saudi authorities are trying to crack down on the number of pilgrims who slip into the holy city without permits and add to massive crowd control problems.
An innovation this year is the construction of a third level at the Jamarat Bridge, from which pilgrims throw pebbles at a concrete wall, representing defiance of the devil.
The bridge near Mina has been one of the worst bottlenecks for traffic. In January 2006, 362 people were crushed to death on the bridge, the worst haj tragedy in 16 years.
Given the political turmoil in the Middle East, the Saudis are also on the alert for any political activity by pilgrims, but the first stages this year have been largely trouble-free.