Hundreds of Nagas (naked ascetic holy men) stand on the riverbank of the Shipra River in Ujjain, Madhya Pradesh, India just moments before plunging in for a ritual bath to mark the Kumbh Mela festival. (From the book What I Eat: Around the World in 80 Diets.) The Kumbh Mela festival is a sacred Hindu pilgrimage held 4 times every 12 years, cycling between the cities of Allahabad, Nasik, Ujjain and Haridwar. Participants of the Mela gather to cleanse themselves spiritually by bathing in the waters of India's sacred rivers. Kumbh Mela is one of the largest religious festivals on earth, attracting millions from all over India and the world. Past Melas have attracted up to 70 million visitors.