The Hajj to Mecca is undoubtedly one of the greatest religious gatherings on earth. It is the requirement in the Five Pillars of Islam which orders every able-bodied Muslim to complete this pilgrimage at least once in their lifetime. With over 1.2 billion Muslims worldwide, the sheer number of people that pass through the gates of Mecca each year is overwhelming. Through special access granted to Discovery Channel, viewers will go behind the scenes and follow engineers, security officers, and medical doctors as they prepare for the influx of pilgrims. See the proceedings from a pilgrim's point of view through the eyes of Australian Matthew Nelson, a recent convert to Islam, as he embarks on his first Hajj. With millions inundating the city, crowd control is top priority for the Ministry of Hajj. Hundreds of deaths have occurred in past decades. In 2006, Saudi officials learnt a painful lesson when a failure in crowd control left more than 350 pilgrims dead at the Jamarat Bridge during the symbolic ritual of stoning huge pillars. Revealed: The Hajj provides the first look at the very latest technologies such as advance logistics software, satellite imaging and computer modelling used by the Command and Control Centre personnel to ensure efficiency and safety. Revealed: The Hajj chronicles how an age old tradition is made possible in the 21st century. Join Discovery Channel on this amazing journey and experience the Hajj like never before.