This is the biggest and oldest temple in Palakkad district and also one amongst the most famous 108 'Durgalayas consecrated by Lord Parasurama. The deities being Annapoorneswari and Mahishasuramardhini. The temple is under the administrative control of Naduvil Madhom Devasom, Thrissur. Situated nearly 6 kms away towards South East of Palakkad town on the banks of 'Sokanasini River, the temple has a legendary and huge compound wall (chuttumathil) having completed gopurams on all 3 sides, with an incomplete portion at the east side - hence called the incomplete temple. The legend is that this huge stone wall was constructed in one night by the 'Bhoothaganams' of the more Devi and when they reached the eastern side, dawn broke and the temple was open for the day and hence they left the structure incomplete. The Sokanasini river flows talong the right side (Valathu) of this temple and hence the name of this place Thiruvalathur. The ancient stone sculptures and writings and the wonderful wood-carved ceilings attract many to this temple. Celebrations like Navarathri festival, Nira, puthari etc are carried out in a grand manner and the most important one is the temple Utsavam Spanning ten days during the month of 'Vrichikam' (November, December) during which 'Thrikkarthika' is celebrated in a unique manner, lighting the thousands of stone lamps surrounding the temple. This festival attracts thousands of devotees and 'Annadanam' is offered to all the devotees on all the ten days of the festival. Numerous devotees are blessed with prosperous and happy married life after offering Swayamvara Pooja in this temple. The temple administration is highly co-operative to render any sort of assistance to the devotees.