Four fairs are recognised as Kumbh Melas -- Haridwar Kumbh Mela, Allahabad Kumbh Mela, Nashik-Trimbakeshwar Simhastha and the Ujjain Simhastha
The Kumbh Mela is held once in 12 years, at a particular venue. The Kumbh Melas at Haridwar and Nashik are held three years apart while those at Nashik and Ujjain are celebrated in the same year or a year apart.
Medieval Hindu mythology has it that Lord Vishnu dropped drops of Amrita (drink of immortality) at four places, while transporting it in a kumbha (which is a pot)
The festival is considered the “world's largest congregation of religious pilgrims”
An estimated 120 million people are said to have visited the Maha Kumbh Mela in Allahabad in 2013, over a two-month period. In fact, over 30 million visited on a single day, on 10 February 2013 (which was Mauni Amavasya)
Until the East India Company rule, the fairs were managed by akharas (sects) of religious ascetics known as the sadhus
In 1820, a stampede at Haridwar killed 430 people
Even Tibet has hosted a festival claimed to be a Kumbh Mela
After visiting the Kumbh Mela of 1895, Mark Twain wrote, “It is wonderful, the power of a faith like that, that can make multitudes upon multitudes of the old and weak and the young and frail enter without hesitation or complaint upon such incredible journeys and endure the resultant miseries without repining.”
There have been numerous documentaries on Kumbh Mela, including Kumbh Mela: The Greatest Show on Earth (2001), and Short Cut to Nirvana: Kumbh Mela (2004) among others.