Believed to have been the capital of the legendary King Mahabali's kingdom, Thrikkakara is home to the only temple in Kerala that is dedicated to Lord Vamana, the fifth incarnation of Lord Vishnu. This temple, the Vamanamoorthy Temple at Thrikkakara is one among the 108 divya deshams or sacred Vishnu temples mentioned in the works of Alvars (saints). 

Located in Ernakulam district, the temple is famous for the exquisite engravings, that depict traditional Onam celebrations, on walls of its sanctum sanctorum. These engravings date back to nearly 2500 years. 

According to legends Lord Vishnu, in his Vamana avatar, set foot in Thrikkakara to visit King Mahabali who was the region's erstwhile king and consigned him to the netherworld. The temple is believed to stand on the exact spot where from King Mahabali is said to have been sent to the netherworld by Lord Vamana. Mahabali was given the permission to visit his land every year on one day, the Thiruvonam day in the Malayalam month of Chingam which is also the Lord Vishnu's birthday. It is this day that is celebrated as Onam all across Kerala. 

In an enormous area of 10 acres, there stands two temples. While one is dedicated to Vamanamoorthy, the main deity in the second one is Lord Shiva. Mahabali's statue is also housed here. For the people of Thrikkakara Onam is much more than just a festival, but rather the most sacred day of the year. The Vamanamoorthy Temple is the epicentre of all Onam celebrations in the state. A grand, special Onasadhya for all who gather, 'Charthu' which is decking up of the deity, processions called Pakalpooram and Seeveli and cultural performances are all a part of the main 10 day annual Onam festival. 

Beyond folktales, the temple also has significance in the history of the land. It is said that the emperor of Kulasekharam, Cheraman Perumal used to conduct annual meetings of all the feudal kings at the Vamanamoorthy Temple. Each year this meeting happened during the festival season that commences on the Thiruvonam day in the month of Karkidakam to Thiruvonam day in the month of Chingam. This month long annual festival concluded with the 10-day celebration of Onam which was from Atham day to Thiruvonam day, in the month of Chingam. A total of 56 local kings, 64 village chieftains and several members of nobility were invited to this festivities without fail. It was when the kings found it difficult to travel to Thrikkakara that the emperor declared that Onam should be celebrated in each household with the deity of Thrikkakara on display. It is believed that it was Cheraman Perumal-Bhaskara Ravi Varma who started the Onam festivities and the festivities were then spread across the state. 

Another story associated with the temple is that Kapila Maharshi visited the temple and offered penance to Lord Vishnu on having heard the tale of Mahabali. It is said that it was the sage who requested Lord Vishnu to be the deity here and that the Lord granted him his wish.