Kaladi near Thrissur is the birthplace of Adi Sankaracharya. It is believed that Sankara's parents Sivaguru and Aryamba offered worship at the Vadakkunnathar shrine at Thrissur prior to their begetting Sankara.

Thrissur is a major railhead on the railroad between Coimbatore and Cochin/Tiruvanandapuram. Near Thrissur is the well visited pilgrimage center Guruvayur. Also nearby are Kodungallur and Tiruvanchikkulam.

The name Thrissur is derived from Tiru Siva Perur. Thrissur was also once known as Vrishachala or the hill of Nandi. Indeed the Vadakkunnathan temple stands on a small hillock and is the most prominent landmark in the town of Thrissur.

Legend has it that the deities Shiva, Sankaranarayana and Rama were installed and worshipped by Parasurama. It is believed that Parasurama, wishing to install an image of Shiva, meditated upon him, only to find an image of Mahavishnu upon opening his eyes. He installed this image as Rama, and then continued his meditation, at the culmination of which he saw a Shivalingam, ie. Shiva on one side and Rama on the other. Upon further continuing his meditation he saw Sankaranarayana or the combined form of Shiva and Vishnu.

There are thus three shrines in this temple - dedicated to Shiva, Rama and Sankaranarayana. Behind Shiva's shrine is a shrine to Parvati.

Vadakkunnathar is worshipped in the form of a mound of ghee or clarified butter. The Shivalingam is enclosed within this ever growing mound of ghee. Ghee is offered during abhishekam, and this 10 feet high mound of ghee stays solid despite the multitude of lamps in the sanctum. The ghee offered over centuries stays here without acquiring any foul odor of any sort.

Other shrines here include those to Vettakkorumakan - a Keralite guardian deity and Ganapati, Dharma Sastha, and Gopalakrishna. There is also a roofless shrine with a Shankh and a Chakra commemorating Aadi Sankaracharya.

The Vadakunnathan temple is a vast one covering a nine acre area, surrounded by fortified wall pierced with towered entrances on all four sides. The circular sanctum is crowned with a conical vimanam. As one enters the temple through the western entrance, a massive Koottambalam or the theater hall is seen to the left. This structure is considered to be a masterpiece of its kind, crowned with three kalasams.

Festivals: Thrissur is the site of the annual Pooram festival attracting thousands, however the festival is not associated with the presiding deity here, although it is conducted in the vicinity of the temple.  Shivaratri is the major festival celebrated in the temple.