Some two million Muslim pilgrims are making their way to Mount Arafat for the pinnacle of the haj festival.
Worshippers are converging on the Mount, some 15 kilometres east of Mecca, as they take the same route the Prophet Mohammad took some 14 centuries ago.
Saudi Arabia’s authorities have mounted a massive security operation over the past week to avert any militant attacks or deadly stampedes.
The pilgrimage has been marred in the past by fires, hotel collapses and police clashes. In one of the worst disasters to hit the event, more than 360 people were crushed to death on a bridge in January 2006.
Since then, Saudi authorities have made improvements to infrastructure to ease the flow of the faithful inside and around the Grand Mosque.
Tomorrow sees the climax of the ceremony with the Eid al-Adha, or feast of the sacrifice, when pilgrims begin the ritual stoning of the devil and walk around the Kaaba.