Millions of pilgrims take bath during Kumbh Mela
This festival occurs four times in a period of twelve years. After every six years Ardh Kumbh Mela is celebrated at Allahabad and Haridwar. And a Maha Kumbh Mela or Purna Kumbh Mela after every twelve years in Allahabad. These festvials are attended by million of peoples. Maha Kumbh Mela of 2001 was attended by 60 million people making it largest gathering in the world.
According to Indian Astrology, Kumbh is celebrated when planet of Brahaspati (Jupiter) moves into the zodiac sign of Kumbh (Aquarius)
Why Kumbh is celebrated at Haridwar, Nasik, Prayag and Ujjain?
Thousands of years ago, Gods had lost their strength, and to regain it, they thought of churning the Ksheera sagara (ocean of milk) for amrit (nectar of immortality), for this they made an agreement with the demons to equally share the amrit. But, when the Kumbha (pot) containing amrit appeared, a fight ensued. This fight continued for twelve days and twelve nights (equivalent to twelve human years). It is believed that during the battle, Garuda(Vehicle of Vishnu) flew away with the kumbh (pot), and the drops of amrit fell at four different places on earth, Prayag, Haridwar, Ujjain, Nasik, so this festival (mela) is celebrated at these places.
Millions of people attend the festival on a single day. The major event is taking ritual bath at the bank of river, important bathing dates are dependent on stellar constellations, other activities includes, religious discussions, devotional singing, mass feeding of holy man, women and poors. On 14 january 2007, the auspicious occasion of makar sankranti over 5 million people participated. Maha Kumbh or Purna Mela is sacred of all pilgrimage. Next festival is occuring in Allahabad in 2013 (January).