There is a very interesting story associated with this temple. There was a great devotee of Lord Vishnu or Lord Ranganatha. He was always busy in serving the Lord and some of his workers have taken advantage of this situation and stolen all the wealth of this devotee. He was not left with even a single penny. But Lord Ranganatha was with him and appeared in his devotees dream and asked him to bring all his workers to the Kollidam river bank. This Devotee reached the river bank along with all his workers and promised to pay them their due amounts. When everyone reached there, Lord Ranganatha appeared as an old man and gave all them some quantity of sand. Those who were genuine and loyal to his devotee, their sand turned in to precious stones but those who cheated him, their sand remained the same. These workers ran behind this old man as they did not get anything and when they were running, the old man turned in Lord Ranganatha and made them realize their mistakes.

There is a lot of importance to this place and temple as well. Pasu is a word meaning Cow in Tamil which is also known as Kaamadhenu. Kaamadhenu is worshiped by Hindus as that will bless with good wealth. When Lord Vishnu or Ranganatha was in Kurma Avaratam, there were many good things and one among those was Kaamadhenu gifted to Lord Indira. During this time, Lord Vishnu appeared in front of Kaamadhenu and hence this place is called as Thiru Aadanur where Aa denotes Cow. There is another fact believed by the people in and around Thanjavur that the idol of Lord Vishnu is growing from past years.

The best time to visit this temple is in the months of May and June as there will be a grand celebration for 10 days which is called s Brahmmotasavam. It is celebrated in the month of Vaikasi.