Young Sri Ram and Lakshman hear about Siddhashrama from Sage Vishvamitra in the Balakanda of the Ramayana. The two young princes were then on their journey along with Sage Vishvamitra to Siddhashrama. Sri Ram and Lakshman were on a mission to protect the yajna of the sage from Rakshasas.
After killing Tadaka in the Tataka Vana, Sage Vishwamitra led the two young princes towards the holy place.
Srihari Vishnu had performed Tapas at Siddhashrama. Vamana incarnation of Vishnu also happened at the holy place.
Sage Vishvamitra had built his ashram at Siddhashrama. He was planning for a yajna for very long time. But it was constantly interrupted by Rakshasas.
Sri Ram and Lakshman vanquished Demons Maricha and Subahu and protected the yajna and sanctity of the place.