St Cadoc's Church is a Church in Wales church located in Caerleon, Newport, Wales and is Grade II* listed. It is one of many buildings associated with the travels of St Cadoc. Caerleon is the historically important site of the Roman legionary fortress of Isca Augusta. St Cadoc's Church stands over the principia (headquarters), where the legionary standards were kept and statues of the Roman emperors venerated. The earliest surviving part of the church dates back to just after the kingdom of Glywysing was overrun by the Normans during the twelfth century and is thought to be the work of Hywel ap Iowerth, who was also the founder of the Cistercian Llantarnam Abbey.