Caernarfon Mithraeum

The Caernarfon Mithraeum is a Mithraic temple or Mithraeum. It was located 137 metres north-east of the Roman castrum of Segontium on the outskirts of modern Caernarfon in Gwynedd, Wales. The remains were discovered by accident on 2 April 1958 and excavated by the National Museum of Wales in August of the following year under the direction of George Boon. The site was found to be already damaged by a sewer trench which cut across the anteroom and had removed part of the southeast corner, but the majority of the temple could be excavated. The excavators noted the site was quite marshy and this suggested that a stream had once flowed close to the temple at the bottom of the shallow valley. The marshy conditions caused the mechanical excavator to frequently fall into the excavation, causing further damage.