Many people are not familiar with it, and yet Kumbh Mela is the largest celebration on earth: depending on the zodiacal positions of Jupiter, the sun, and the moon, Hindus travel to certain places along holy rivers, the Ganges for example, for the purpose of bathing and cleansing themselves of sin. In 1989 fifteen million people are said to have attended, in 2001 around thirty million, and in 2013 approximately thirty-four million. In order to transport, house, and feed these enormous crowds of people, functioning temporary structures are required, which in each case are created by the communities hosting the gathering. In 2013, a team from Harvard University monitored the large-scale event from its preparation to the actual celebration itself. The fascinating prototypes for flexible urban planning were investigated and documented, and the organizers received advice in issues around environmental protection. The volume presents the comprehensive research findings and includes city maps, aerial images, and photographs-for instance a spectacular photo series by Iwan Baan.