Thiruvithamcode Arappally ("Royal Church"; Tamil: ; Malayalam:? ;), or Thomayar Kovil or St. Mary's Orthodox Church, is a church located in Thiruvithamcode in Kanyakumari District, Tamil Nadu state in India. It is believed by the Christian communities in Kerala that the historic Thiruvithamcode Arappally, also called Amalagiri church as named by the Chera King Uthiyan Cheralathan, was built by St. Thomas, known as the Apostle of India, in 63 AD. It is believed to be the world's oldest existing church structure, and believed to be built by Thomas the Apostle in 57 AD, and is now declared an international St. Thomas pilgrim center.
It claims to be the world's oldest church that still has daily prayers and India's oldest church that hasn't been reconstructed till now. The church has three main parts built in the 17th century and a 20th-century entrance hall. Its walls are built of locally quarried stone, chiseled with a multi-tipped chisel, a technique known in Kerala and possibly introduced there by foreign contact in the 16th century.
Thiruvithamcode (also spelled Thiruvithancode, Thiruvithankodu and Thiruvithangodu) is a small panchayat town located in the Kanyakumari district of the Indian state of Tamil Nadu. It is about 20 km from Nagercoil, and 2 km from Thuckalay.
The church today is maintained by the Malankara Orthodox Syrian Church. Catholicos of the East and Malankara Metropolitan, Baselios Marthoma Didymos I proclaimed the church as an international St. Thomas pilgrim center on 16 December 2007.