The annual hajj, the pilgrimage to Mecca, Saudi Arabia -- Islam's most holy city -- is receiving $227 billion in improvements in a 30-year project. The pilgrimage, ordained by the prophet Muhammad as one of Islam's five pillars, attracted fewer than 100,000 followers annually until air travel made the journey easier. The demand for pilgrim visas is such that about 2 million people are allowed to attend, and the hajj waiting list is 12 years long. It was an incident in 2006, in which those arriving to perform the rite of throwing stones at the Jaramat walls, in imitation of Muhammad's renouncement of the devil, collided with those departing. In the panic and crush of bodies, at least 345 people died and over 1,000 were injured. The incident occurred days after 76 pilgrims died when their hostel in Mecca collapsed, and the Saudi royal family, which safeguards Mecca and other holy cities, decided changes were in order. Engineering firms worldwide are preparing Mecca for a massive development -- including the Canadian architectural firm Moriyama and Teshima and the engineering firm MMM Group, which uses mapping software first developed in Canada to locate water resources in the area. MMM was charged with learning how much water and electricity the new Mecca would need during the pilgrimage. The millions who arrive overwhelm the city's water and sewage capabilities. "I tell the young bucks they will never work on a project like this again. It's once in a lifetime," said MMM's Hugh O'Donnell.