Mor Baselios Cathedral at Mount Sinai, Kothamangalam, is situated adjacent to Mor Ignatius Seminary which is the bishop's house (presently the residence of the Catholicos) and the Angamali diocesan headquarters. The three acres of land where the Cathedral and the diocesan headquarters is situated was bought by the Kothamangalam MarThoma church (Cheriapally) and the Mar Athanasius College Association jointly. The construction work of the Mor Baselios Cathedral started immediately after the completion of the Diocesan headquarters in January 1998. It was Rev. Fr. Varghese Maikulangara who donated the entire amount required for the construction of the cathedral. On Dec 11, 1998, the diocesan Metropolitan H.G. Thomas Mor Dionysius (Catholicose Aboon Mor Baselios Thomas I) consecrated the new church and the first Holy Qurbono was celebrated the very next day by the Chief Metropolitan of the East H.G. Abraham Mor Clemis of Knanaya diocese.

While the main 'thronos' (altar) of the cathedral is dedicated to St. Baselios Yeldho Bava, the patron saint of the church, the other altars are in the names of St.Mary, Mor Geevarghese Sahado (St.George), Patriarch St. Ignatius Elias III and St.Gregorios Chathuruthy.

The most important festival of the church is celebrated on the Sunday just before the famous 'Kanni 20 Perunnal' of the Kothamangalam Marthoma Church. It usually comes in the last week of September.

Source:

    Directory of the Angamali diocese, 2003