Many ancient Shiva Temples could be witnessed in Kashi. one of them is the Agasthyeshwar Temple. The importance of this Temple as well as Agasthya Kund is mentioned in Kashi Khand.
Legend
When Sage Narad encountered the Vindhya Mountains, he informed them that Sumeru Mountain was rising in elevation and would soon exceed Vindhya Mountain. This alarmed Vindhya Mountain, which began to rise steadily. He obstructed a large portion of the planet from receiving sunlight in the process. The result was mayhem. Plants, animals, and other living things all began to perish.
Devas and other intelligent beings rushed to Lord Brahma and begged him to step in. They were told by Lord Brahma to travel to Kashi and discuss the situation with Sage Agasthya. Devas arrived in Kashi with Brihaspati and immediately went to the ashram of Sage Agasthya.
They witnessed a peaceful scene where the Sage was praising Lord Shiva in the shape of a Shiv Ling that had been set up by earlier. Agasthyeshwar was the name of the Shiv Ling. To worship Lord Shiva, Sage Agasthya performed all the pooja and rites in a Kund he had dug, which came to be known as Agasthya Kund. The serene and heavenly atmosphere of the Ashram is thoroughly described in Chapter 3 of Kashi Khand.
The entire advantages of being in Kashi would accrue to devotees who take a dip in Agasthya Kund and carry out the rites for their ancestors. (Chapter 26 of Kashi Khand)
According to Kashi Khand Chapter 61, The rites for the devotees’ ancestors should be carried out when taking a dip in Agasthya Kund. They ought to honor Agasthyeshwar. Such followers will have all of their sins forgiven. After they pass away, all of their pain will be forgotten and they will enter paradise.
