Sri Rama installed the Siva Lingam here to atone for the sin of killing Ravana, a Brahman. He selected this beautiful valley surrounded by hills and verdant greenery for the purpose and ordered Hanuman to bring a Sivlingam from Varanasi. Hanuman was late in arriving with the Siva lingam and as the auspicious hour was nearing, Lord Siva himself appeared before Sri Rama and presented a Sivilingam for installation. Hence the lingam in the temple is called Swayambhu Linga. It is also called Ramalingeswara as lord Sri Rama had installed the lingam.

Hanuman returned with 101 lingams for selection from Varanasi and felt aggrieved at not having his lingam installed. Hence he threw them all over the area. Even to this day several lingams are found scattered all over the place outside the temple.

To mollify Hanuman, Sri Rama ordained that precedence would be given to him for worship at the temple. He also said that the hillock where the lingam was installed would bear his name kesarigiri that is, Hanuman, the son of Kesari. Over a period of time, it has colloquially transformed and is now known as Keesara and the hill as Keesaragutta. Ever since, the rituals follow the command of Sri Rama.