Church of St. Teilo was probably built in the 12th century. During the Middle Ages, Llantilio Crossenny was the seat of the Llandaff bishops, which resulted in the extraordinary scale of the extension of the temple. In the 13th century, the building was enlarged by a nave and a tower, and in the 14th century, the chancel was rebuilt and a northern chapel was added. In the fifteenth century, the corpus of the temple was rebuilt into a basilica with two aisles and a clerestorium illuminating the nave. In 1708, a spire was added to the tower, and the windows of the southern nave were modernized in 1857, during the Victorian renovation.
The church was built of red sandstone, from the fifteenth century it consisted of a three-nave corpus in the form of a five-span basilica, two transepts, the central tower and chancel, built on a cruciform plan. From the north to the transept, a rectangular chapel was placed in the 14th century. The western façade is preceded by a porch, on which both sides are visible narrow, longitudinal ogival windows, belonging to the oldest phase of the temple’s development. The east side of the church is completed with a four-sided chancel with a single, large, gothic window from the 14th century. Centrally located tower at the intersection of the nave’s, has a bifora on each side, with each opening crowned with trefoli. Only the western window is partially obscured by the raised nave. The windows of the side aisles and the clerestorium were mostly replaced during the 19th-century renovation.
The church at Llantilio Crossenny is one of the most magnificent medieval sacral buildings in Wales, both because of its excellent state of preservation and the remarkable scale of construction, contrasting with the small town. The temple still performs sacral functions, but it is also open to visitors.
Wooding J., Yates N., A Guide to the churches and chapels of Wales, Cardiff 2011.
Website britishlistedbuildings.co.uk, Church of St Teilo A Grade I Listed Building in Llantilio Crossenny, Monmouthshire.