Once the Lord, in the form of Kriti Vaseswara, was sitting with Goddess Uma Devi, when Nandi offered his prayers and said that there are 68 shrines dedicated to Lord Shiva in this holy place. Many idols/Shivling have been brought from many places and installed in Kashi.
In the holy city of Kashi, a linga named Tripurantaka has appeared from Shri Shail Parvat, which is called Tripurantakeshwar. Worshiping this deity gives the devotee the benefit of worshiping the holy Shri Shail Parvat. A devotee who worships Tripurantakeshwar will attain salvation and need not worry about rebirth.
There are twelve Jyotirlingas on all India basis and there are twelve important Shiva Lingas in Kashi which represent the above mentioned twelve Jyotirlingas. Tripurantakeshwara is worshiped as Mallikarjuna Jyotirlinga (Sri Salem, Andhra Pradesh).