Muslims from across the world are in Mecca in Saudi Arabia for the annual Hajj, the mandatory Islamic pilgrimage which lasts for five days.
More than two million Muslims from around the world started the five-day Hajj pilgrimage at Islam's holiest sites in Saudi Arabia on Wednesday, a religious duty and an epic multi-stage journey.
It is an increase in number from 1.86 million last year and just 24,000 in 1941.
Saudi Arabia has received credit for its management of the massive crowds that descend upon Mecca each year.
It is mandatory for all Muslims who fit certain requirements to perform the pilgrimage at least once in a lifetime.
Some basic requirements include being sane and having reached puberty.
"New emotions every time"
No matter a person's colour or status, all pilgrims dress the same, in a simple white cloth wrapped around their bodies – a sign of equality among all as they pray to one God.
They then head for Mina, five km east of Mecca, where hundreds of thousands of people will gather before setting off on Thursday at dawn to climb Mount Arafat, the pinnacle of the pilgrimage.
Tidjani Traore, a public service consultant from Benin, said he was preparing for his 22nd pilgrimage at the age of 53.
"Every time, there are new emotions," he said. "There are new innovations for organising and hosting the pilgrims. Now, for example, the tents are air-conditioned."
Saudi authorities have placed misting fans on the esplanade of the Grand Mosque to take the edge off the intense heat.
On the eve of the first rites of the pilgrimage, the walkways thronged with people and the smell of musk wafted through the air.
Sitting in the shade of trees or reinforced concrete bridges, the faithful waited patiently for the next call to prayer. Others continued their march, protected by a prayer mat or a small umbrella fixed on the head with an elastic band.
Interior ministry spokesman General Mansour al Turki said more than 100,000 security personnel had been deployed at various sites along the hajj route.
Some 17,000 civil defence employees backed by 3,000 vehicles are also helping with security, and thousands of security cameras have been set up along the pilgrimage route, according to a civil defence spokesman.
Saudi Arabia hopes to welcome 30 million pilgrims annually in the kingdom by 2030, the Saudi Gazette said, up from the current eight million.
Muslims also flock to the country for the umrah pilgrimage, which can be performed at any time of the year.
Saudi authorities say they are ready for any eventuality.
Saudi authorities have mobilised vast resources in the hope of avoiding a repeat of a deadly 2015 stampede that left nearly 2,300 people dead, including 464 Iranians.
This year sees pilgrims from Iran return after a hiatus following a diplomatic spat between it and arch-rival Saudi Arabia.
It also comes with the Gulf mired in political crisis and Daesh under pressure in Iraq and Syria.
Riyadh and Tehran cut ties months later, after the execution of a Shia cleric in Saudi Arabia sparked attacks on Saudi diplomatic missions in Iran.
Qatar crisis raises tensions
The pilgrimage also comes amid a diplomatic crisis between a Saudi-led bloc of Arab countries and Qatar, accused of supporting militant groups and being too close to Riyadh's arch-rival Tehran.
A blockade imposed on Qatar since June 5 has seen sea and air links shut down, preventing many Qataris from making Hajj, although Riyadh claims to have relaxed entry restrictions across its land border with Qatar two weeks before the pilgrimage.