Leaving the breathtaking views of Prinsep Ghat behind, circular rail moves further south and crosses the Adi Ganga bridge before getting on to the elevated tracks. If mythology is to be believed and considered, then the Adi Ganga used to be the original course of Ganga in the ancient period. The bridge marks that point from where the Ganga switched route to its present course over time. Many old literary works like Manasa Mangal and others bear testimony to this fact. The Adi Ganga is also famous as Gobindapur Creek, Surmans Nulla, or Tolly's Nulla.

In the eighteenth century when it marked the border of the Gobindapur village, it was called Gobindapur Creek. Edward Surman, the leader of the Brithish Ambassy to Delhi in 1717, had carried out dredgeding in the river. Adi Ganga is refferd to as 'Tolly's Nulla' after a British Major, William Tolly, who took the endeavour and connected the Adi Ganga River to the Circular Canal in 1773. In 1775 he connected it to Vidyadhari. At present it flows by a number of places like Tollygunge Azadgarh, Alipore, Netaji Nagar, Rani Kuthi, Bansdroni, Garia, Naktala, Rathtala, Boral, Narendrapur, Mahamayatala, Harinavi, Rajpur, Changaripota, Kodalia etc. The holy and famous Kali temple of the city at Kalighat is located on this river. It flows on to Joynagar and finally joins the Bay of Bengal.