Kashi Khand, Chapter 100 states that devotees should undertake religious tours (Yatra) of various deities situated inside the main area of Kashi. the importance of the Aadi Mahadev temple is mentioned in Kashi Khand.
Legend
In Satya Yug, one Ling revealed itself from the Bhoomi in answer to the sincere pleas of Devas and Rishis. Mahadev Ling became the name given to this. This Ling is credited for turning Kashi into a Mukti Kshetra (region free from bondage). Even if he passes away anywhere other than Kashi, a person who devotedly does pooja and Archana at this temple will pass into Lord Shiva‘s abode after death.
Sincere prayers to Lord Mahadev in Kashi have the Punya equivalent of prayers to all accessible lings worldwide. Pooja at the Mahadev temple at least once ensures that the performer will have a position in Lord Shiva’s abode after death (Kashi Khand, ibid).
Yagyopaveeth (Sacred Thread) offerings are given special attention at the Mahadev Temple on Chaturdasi Day after Amavasya in the Shravan Month (July-August) (Kashi Khand, ibid). The temple’s current name is Aadi Mahadev Temple.
