This is adhishtana or presiding deity of Haridwar.
The ancient temple is widely regarded as one of the 51 Shakthipeethas of Godess Sathi. It is believed navel and heart part of Goddess Sathi fell here.For more on this story please visit section on 51 Shakthipeethas.
This is one of the three oldest surviving temples in Haridwar. The other two being Bhairava temple and Narayana Shila temple.
Earlier Haridwar is also known as Mayapuri. The name is derived from this Goddess.