Hindu devotees pray as they attend the first "Shahi Snan" at the ongoing "Kumbh Mela", or Pitcher Festival, in Allahabad
The 2013 Maha Kumbh Mela, the world's largest religious gatherings, began in Allahabad on Monday on the auspicious day of Makar Sankranti with tens of thousands devotes taking the ritual bath in holy river Ganges.
At least 1.1 crore devotees from around the world are expected to take part in the 55-day festival held at Sangam in Uttar Pradesh. Sangam is the meeting place of three holy rivers - Ganges, Yamuna and the mythical Sarasvati.
The Maha Kumbh Mela takes place every 12 years at four places - Allahabad, Haridwar, Ujjain, and Nashik. The mela alternates between these four places every three years.
The next festival will take place in 2016 at Ujjain, Madhya Pradesh, on the banks of the river Shipra, where it is also known as "Simhastha".
With matted hair and ash smeared all over their bodies, thousands of Naga sadhus and Hindu-Shaivite ascetics marched naked to the sangam to take bath in the holy water.
Over 50,000 policemen have been positioned across the city to keep order at the festival, and also to prevent any terrorist attacks and stampedes of pilgrims during the Mela.
"The day went off without any incident. The bathing went off peacefully," senior superintendent of police RKS Rathore told the BBC.
More than 100 foreign media personnel and over 500 local and national media persons attended the first day of the Kumbh Mela.
"This is huge," said Nick Oza, a photo-journalist from Arizona told The Times of India. "I don't know from where to begin and where to end!"