The Nilachal Hill  or  Kamagiri hill situated at a distance of 7 km from Guwahati is of great historical, archeological as well as religious importance. This hill believed to be a ‘Khasi’ sacrificial site earlier, now has a group of ancient temples on the top; the largely eminent of them is the Kamakhya temple. The temple of Goddess Shakti or Kamakhya is the oldest and most revered centre for Shakti worship leading to the spread of the Tantrik Hinduism sect .

It is believed that female genitalia (yoni) of dead Sati fell down while her corpse was being carried by her husband Shiva turning the hill blue, therefore the name Neelachal (Blue Spread).

There is no image of Shakti here. Within a corner of a cave in the temple, there is a sculptured image of the Yoni of the Goddess, which is the object of reverence. A natural spring keeps the stone moist.

Other temples on the Neelachala hill include those of Tara, Bhairavi, Bhuvaneswari and Ghantakarna.

Durga Puja is celebrated annually during Navaratri in the month of September- October. It is a three day festival attracting several visitors. A unique festival observed here is the Ambuvaci (Ameti) fertility festival wherein it is believed that the Goddess (mother Earth) undergoes her menstrual period. During this period the temple is closed for three days and opened with great festivity on the fourth day. It is believed to be inauspicious to till the ground or to plant seeds, during this three day period.