As pilgrims complete the first of the three days of symbolically stoning the devil, security personnel keep watch over the crowd from a command and control centre located in Mina.
Under a bank of monitors broadcasting live footage from more than 5,000 cameras, Saudi officers have kept their eyes on every route and gathering spot at this year's hajj pilgrimage.
As pilgrims complete the first of the three days of Tashriq, a period wherein pilgrims symbolically stone the devil in Mina, Saudi authorities have been at pains to assure the world that every possible measure has been taken to prevent a repeat of last year's disaster at the hajj that cost the lives of around 2,300 pilgrims in a stampede.
An "eye" which never closes forms the heart of the command and control centre located in Mina, near Mecca, said Colonel Saad al-Dosari, its planning chief.
Another officer, Captain Tareq al-Azam, told AFP that his dozens-strong team has been on duty around the clock monitoring this year's 1.8 million pilgrims who have converged on the desert kingdom from across the globe.
More than 5,000 cameras have been installed in the entire Mecca sector covering a radius of around 10 kilometres (six miles) around its Grand Mosque, the single holiest place in Islam.
From his vantage point, the captain can direct the cameras and is able to zoom in to investigate any suspicious-looking or potentially dangerous activity.
Dozens of soldiers are posted at the centre, located a few metres away, with headphones on and microphones at the ready to pass on information to the tens of thousands of members of the security forces on the ground.
Having completed the mandatory rituals including the trimming of the hair and the slaughtering of an animal, pilgrims will now return to Mecca to perform the farewell circumambulation around the Kaaba.
This year's hajj, which started last Saturday and ends on Thursday, has been free of any major incident.