A multitude of Muslims from around the world gathered in Saudi Arabia on Sunday, making their final preparations for the annual hajj pilgrimage, which is one of the central tenants of Islam.
Saudi officials say over 1.6 million Muslims have assembled for the hajj, which begins on Monday, the eighth day of the month of Dhi al-Hajja under the lunar calendar.
Hundreds of thousands of Saudi faithful as well as foreigners living in the desert kingdom will also be taking part.
All Muslims are required to make the hajj to Mecca, in the western region of the kingdom, at least once in their lifetime if they have the means to do so.
Among this year's pilgrims will be Iranian President Mahmoud Ahmadinejad, who will be the first president of the Islamic republic to take part in the holy event.
He will join other pilgrims in carrying out a series of sacred rituals, which includes walking counter-clockwise seven times around the Kaaba, a cube-shaped structure in Mecca toward which Muslims pray.
Muslims believe the Kaaba is the first building on earth and that it was originally constructed by Adam. According to them, it was rebuilt by the prophet Abraham and his son Ishmael some 5,000 years ago.
The Kaaba houses the Black Stone, which Muslims believe was sent from heaven by the angel Gabriel to Ishmael. The stone was revered even in pre-Islamic times by pagans.
Nearly 2.4 million people flocked to Saudi Arabia to perform the last hajj, including more than 1.6 million from outside the kingdom, which is the birthplace of Islam.
Saudi Arabia has announced that the high point of the hajj, when pilgrims converge on Mount Arafat near Mecca, will take place on Tuesday.
The following day will be Eid al-Adha, the Feast of the Sacrifice, when Muslims slaughter lambs to mark the end of the pilgrimage.
A total of 11,000 doctors, nurses and paramedics will be on hand to provide medical care, with 4,200 beds at 21 hospitals and 145 health centres in the holy sites of Mecca, Mina and Arafat, local media reported.
According to the official SPA news agency, 85 ambulances have also been mobilised for the occasion and health alerts will be issued in case of any outbreaks of disease.
The precautions and security measures are in place to try to prevent a repeat of the high death tolls that have often characterised past pilgrimages. In 2006, for example, 364 people were killed in a stampede at the entrance of the Jamarat Bridge, where Muslims cast stones at a pillar representing Satan.
The stoning ritual has created some of the worst scenes of panic during the hajj, including one in 2004 when 251 pilgrims died, and in 1994 when 270 perished in a stampede.
"Saudi Arabia has mobilised all the needed security and municipal forces for a smooth hajj, so hopefully we will not see any problems," the Saudi Interior Minister Prince Nayef bin Abdul Aziz, who heads the hajj supreme committee told reporters on Saturday.
Local media reported on Monday that oil-rich Saudi Arabia planned to build a five billion dollar monorail network that would provide safer and faster transport for pilgrims travelling between holy sites.
The hajj is one the five pillars, or tenants, of Islam that followers of the religion must abide by. The others are fasting the holy of Ramadan, praying five times each day, the Shahadah (the profession of the faith) and the Zakat (the giving of alms to the needy).