Legend says nectar from Samudra Manthan fell in four cities, forming Kumbh Mela.
During British rule, Kumbh Mela was used by leaders to promote nationalist ideals.
UNESCO designated Kumbh Mela as "Intangible Cultural Heritage of Humanity" for its global significance.
Underwater and tethered drones introduced for surveillance and crowd monitoring at Kumbh Mela.
Kumbh Mela in Prayagraj projected to generate Rs 2 lakh crore revenue.