Praying at the Great Mosque multiplies blessings by a thousand, goes the saying. Simply being able to see it and listen to the prayers seems to be enough for some pilgrims. The magnitude of the Hajj also places a steep financial burden on the Saudi authorities in terms of street cleaners, security, transportation, water supply and continued research. In the past couple of years, the Hajj Research Centre has focused on getting the pilgrims safely through the Al-Jamarat location at Mina. Here, three stone pillars set some 200 metres apart represent the devil's three appearances before the prophet Ibrahim, or Abraham.
Pilgrims throw pebbles to cast away Satan in the same way Ibrahim is said to have done.
Getting the flow of thousands of pilgrims past the pillars smoothly is perhaps the biggest logistical challenge. A two-layered bridge has been built, with the pillars poking through walled holes in the top level, so pilgrims can cast their pebbles above and below simultaneously. Still, it's in the confines of this relatively narrow area that one person stumbling causes a chain reaction. Researchers are looking to limit the pace and flow of pilgrims heading to the pillars, to avoid crowds building up. They'll watch carefully this year to see if that works.