Some of the historians believe that Vadakkunnathan temple was at one time Buddhist shrines. In the Vadakkunnathan temple just outside the western gopuram there is a peepal tree with a paved platform, which is called "Sreemoola-sthanam." It is believed that at this very spot Parasurama, after consecrating the deities of the temple, had met the Nambudiri Brahmins, the traditional priests of Kerala temples, and had handed over charge of the temple to them and had disappeared.
There is an interesting story told in this connection. Before disappearing himself, Parasurama had told the Nambudiri Brahmins of Kerala that if they met with any serious difficulty they could observe a certain ritualistic fasts and invoke his presence and he would come to their aid. Several years passed. Once the Nambudiris thought that they should conduct a test to see if Parasurama would appear again before them. Accordingly they observed the prescribed fast. And Parasurama did appear to their surprise. When he enquired about their trouble the Nambudiris had to confess that they invoked him only as a test. At this, the sage got angry. Saying that he would never again appear before them he disappeared for ever.
A striking feature of the temple is the kuttambalam which one sees on the left side as one enters the temple through the western gopuram. This is the theatre hall for staging kuttu, an ancient dramatic form of art famous in Kerala. There are kuttambalams in several temples in Kerala but there are few structures which are as large and as beautiful as the one at Trichur. It is a marvel of structural workmanship with sloping roofs of carefully enmeshed copper plates, austere, dignified and aloof. With the three finials shining at the top this 'playhouse for Gods and Goddesses, for the worshippers and the worshipped' has an imposing appearance.
There is an interesting story about its construction which was planned by "Vellanazhi" Nambudiri known for his skill and knowledge of Thachu Sastra (architecture). There was an old and dilapidated .structure at the same place where the present kuttambalam stands where Vellanazhi was ordered to build a new structure by the then Diwan Sankunni Varrier. All he did was to go to the temple with his carpenter and pray to the Lord for a while. He then went inside the old structure, spread a cloth and lay on it for an hour. Then he came out and ordered the carpenter to demolish the old structure and start building a new one. The perplexed carpenter asked where the "Puram Kuttu" or sketch was. The Nambudiri replied that he had already made 'Akam Kuttu' (mental sketch) and asked him to go ahead as he ordered. The final result was the beautiful structure which is found today.
The Highness was very much pleased with the skill of the Nambudiri. He wanted to test his skill on another occasion. He asked him to reconstruct the outer wall of the temple and wanted to know the exact number of bricks that would be required. The Nambudiri thought for a while and gave a number. The king had warned him that he would take him to task if the number was found less or more.
Then he asked one of his trusted men to get the exact number asked for but hide two bricks somewhere when the wall was completed finally, two bricks were still required. The king asked the Nambudiri's explanation. He fearlessly had told him that the kings men had either brought two bricks less or hidden them elsewhere. The pleased king presented him with a golden bracelet. Such was the skill of the architect.
There is another amusing story about the origin of the white rishabha or bull at the main entrance to the nalam-balam from the west. Once, a young and handsome saint visited the temple. He sat on the mandapam in front of the sanctum and meditated for hours together. He disappeared the moment the temple was closed and appeared again when the same was reopened. He was so attractive that many people especially women who came to worship stood and stared at him. After a few months the children born to several women in this place resembled the saint. The men became angry at this and wanted to drive him away.
The saint understood this. So he brought skilled artisans from Tamil Nadu and had a beautiful bull made and installed it at the entrance to the temple. Now several cows grazing in the temple yard came near the bull and stood as though admiring the beauty of the bull. The newly born calves also had resemblance to this bull. It was then that the people realised that on whichever object pregnant women concentrated during their pregnancy the child would resemble that object.