The pilgrims — men dressed in identical seamless white garb and women covered except for their hands and faces — circled the Kaaba on Thursday, at the Grand Mosque, Islam's holiest site, in the first ritual of the pilgrimage.
The Kaaba is a large cubic structure that Muslims face during their five daily prayers. Muslims consider the Kaaba as the house of God and believe it was built by Ibrahim and his son Ismail.
Authorities were bracing themselves for heavy showers in Mecca over the next few days, likely to turn Mina — a huge tent city that only comes alive during the pilgrimage — into a muddy, slippery camp. There were also concerns over power outages and rocks sliding off surrounding mountains.
While the sky was clear Thursday, weather reports forecast cloudy skies and the possibility of rain starting Friday.
Saudi authorities, however, said they were fully prepared, with more than 2,000 rescue vehicles and 118 boats at their disposal, according to Lt. Gen. Saad al-Tuweijry, head of the Civil Defense.
To ease water drainage, the municipality has widened the water passages in the mountains surrounding the area and worked on supporting huge rocks.
Thirty hospitals and several health centers have also provided more than 150 ambulances and over 4,000 beds. The total cost of developing, maintaining, and building new health projects this year reached more that$16.5 million.
After the visit to the Grand Mosque, which fits 460,000 people inside, the pilgrims head to Mina, where some 44,000 white, fireproof tents have been set up at a cost of $640 million. In addition, the cost for other infrastructure in the city were estimated at more than $1 billion.
The hajj has been marred by tragedies in the past. In 1997, a fire aided by high winds swept through Mina, killing more than 340 and injuring 1,500.
Qassem Saleh, an Indonesian businessman, said this was his ninth pilgrimage.
"We're talking about the most sacred place in the world," he said.
Following last year's terrorist bombings in the kingdom, which killed 51 people, authorities have increased their vigilance and deployed thousands of troops to maintain the peace.
Saleh said his faith in God outweighed his fear.
"We of course heard about the explosions and definitely there are so many concerns among many pilgrims, but there is nothing we can do but to depend on God," he said.
"It is not for religious reasons that they do what they do, they are after political gains," he said, adding "but we are not here to be involved in politics, we are here to perform a religious duty at the heart of Islam."
The tent city can host up to 3 million pilgrims, but so far 1.3 million have arrived from outside the kingdom and are expected to be joined by some half a million from inside Saudi Arabia.
According to Hajj Minister Iyad Madani, 1.5 million pilgrims from outside the country will perform the rituals this year.
The hajj peaks Saturday with prayers at Mount Arafat, a gentle hill 12 miles southwest of Mecca. The time spent at Mount Arafat is believed to symbolize Judgment Day, when Islam says every person will stand before God and answer for his deeds.