Millions of people have arrived in Mecca for the annual Islamic haj pilgrimage to the site. Haj is a religious duty for all Muslims, both Sunni and Shi-ite, and they are expected to go to Mecca at least once in their lives, if they can.
The Saudi Arabian authorities have said that they will not tolerate any disruptive political demonstrations or trouble-making and have paraded water-canon, tear-gas launchers and even truck-mounted machine guns.
Many of the pilgrims are praying for peace in Libya and Syria as well as other countries in the Arab world. The centre of the celebrations is the Grand Mosque, which is often so full that pilgrims sleep on the pavement outside in order to secure their entrance the next day.
The haj attracts up to six million Muslims from all across the world every year. This year, the Eid al-Adha celebrations coincide with the haj, and will start on Thursday.