St. Mary's Orthodox Syrian Cathedral, located at a distance of 15 km from Adoor town, is an ancient place of worship. Situated in the village of Thumpamon, the church is more widely known as Thumpamon Valiyapally. It is believed that this church was the worship centre of a group (known as Nazarene Christians) who settled in the region many centuries ago. Though this is the popular belief that there is no written evidence to prove this fact.
According to history, the church was built in 717 AD. A story goes that after returning from Jerusalem, Parumala Kochu Thirumeni gave this church the title of The Little Jerusalem Church. St. Mary's Orthodox Syrian Cathedral is the headquarters of Thumpamon Diocese of the Malankara Orthodox Syrian Church. This church is one of the oldest churches in Kerala and has contributed to the history and culture of the region.