Beginnings of the church of St. John in Llandenny dates back to the twelfth century. In the fourteenth century it was extended by the chancel, and in the next century the tower was erected and the roofs were replaced. In the years 1860-1865, John Prichard and John Pollard Seddon carried out a successful renovation of the building. Subsequent repair works were carried out at the beginning of the 20th century.
The church was built of Old Red Sandstone, and its roofs were covered with stone tiles. It consists of the twelfth-century, rectangular nave, narrower and shorter, rectangular chancel on the east side and a tower from the fifteenth century located on the west. To the southern wall of the nave, a porch was added in the fourteenth or fifteenth century, while the northern sacristy is an early modern addition. The windows of the nave come from the fifteenth century, and in the chancel there are visible 14th-century openings, crowned with trefoils. The three-stepped tower is crowned with a crenelage and in the north – east corner it has a communication turret. Inside the church, originally the presbytery was separated from the nave by the rood screen, but only the south staircase, extended by a projection from the nave, remaines.
Website britishlistedbuildings.co.uk, Church of St John. A Grade I Listed Building in Raglan, Monmouthshire.