The church of St. Peter, Paul and John in Llantrisant was founded in the 14th century. In the fifteenth and sixteenth centuries, it was significantly expanded, among others, a tower was erected at that time. The date of 1593 engraved in the nave, means rather royal visit, than the next reconstruction. Victorian renovation the church passed in the second half of the nineteenth century.
The church consists of a wide nave on a rectangular plan, a narrower and shorter chancel, also on the plan of a rectangle, a massive tower on the west side and a southern porch. The tower is topped with a decorative battlement and has a communication turret on the south-eastern side. On the south side of the nave there is a projection, which probably housed the internal stairs to the rood screen second floor, separating the nave from the presbytery. The windows were mostly renovated or replaced in the 19th century. The late medieval window with the tracery is located in the eastern wall of the chancel. Inside, on the southern wall of the choir, there is a large piscina with a canopy topped with a trefoil.
Website britishlistedbuildings.co.uk, Church of Saints Peter, Paul and John A Grade I Listed Building in Llantrisant Fawr, Monmouthshire.