Kumbh Mela festival: The world's largest religious festival, India's Kumbh Mela begins in Prayagraj on January 15. The 49-day festival attracts millions of Hindu pilgrims to the sacred waters of the "sangam," where the Ganges, Yamuna and Saraswati rivers meet.
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Holy dip: Bathing in the sacred waters is believed to achieve "moksha," or salvation, from the cycle of life and death.
Royal entry: One of the most striking sights of the festival is the "shahi," or royal procession of the dramatic Hindu holy men known as "sadhus." Some are dressed in saffron, others sporting dreadlocks and smeared in ash as they make their way to to the river to take their first holy dip.
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Alternating cities: The Kumbh Mela takes place four times within a 12-year period, alternating from city to city every three years. The Maha (mega) Kumbh takes place every 12 years.
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Largest-ever human gathering: In 2013, an estimated 120 million people joined the great Maha Kumbh Mela in Prayagraj.
Massive pop-up bridges: Patoon bridges are built for holy men to cross during the Kumbh Mela festival.