Construction of the church of St. Mary in Caernarfon began around 1307, when Henry of Ellerton, assistant, and then masonry master of the Caernarfon Castle, obtained permission from the king to build a family chapel. The scale of the building indicates, however, that originally it was to serve as a temple for a garrison stationed in the city. The construction of the church was completed around 1315. The church was restored in 1811-1814 by architect Benjamin Wyatt from Penrhyn Estate, who rebuilt the southern and eastern walls and moved one window to another place.
The church was erected in the corner of the town walls, which form the north and west walls of the temple. The corner cylindrical tower, called the Bell Tower, in addition to the defensive functions, also housed the church sacristy and a room for the chaplain. The church itself is a three-nave structure on a rectangular plan. The southern aisle consists of five bays, supported from the outside by stepped buttresses, with the crowning in the form of massive pinnacles. Between them there are three ogival windows with traceries. The northern aisle is similar to the southern one, but it is based on a defensive wall, and therefore did not need a buttresses. It is pierced also with three ogival windows. The central nave on the western side has a single pointed arch window with a tracery, which was originally located on the eastern side. The porches on the south side are a nineteenth-century addition.
Website britishlistedbuildings.co.uk, Church of St Mary A Grade I Listed Building in Caernarfon, Gwynedd.
Website coflein.gov.uk, St Mary’s church, Caernarfon.