ABSTRACT
The church of St Seiriol at Penmon on Mon contains two or three phases of work that are datable to the first third of the 12th century and belong among the earliest manifestations of the Romanesque style in Wales. The building thus deserves detailed consideration for the light it throws on cultural interaction in Gwynedd at the beginning of the 12th century. Historical sources suggest that the patron was Gruffudd Ap Cynan. The church at Penmon contains more than one phase of Romanesque work, but the exact sequence of construction is uncertain in the absence of a published detailed archaeological study of the building. It is difficult to be certain how to reconstruct the actual state of a Cairs in the 12th century on the basis of the documentary references. The first would be that the mainland site at Penmon was an independent institution that coalesced with the separate insular site at Ynys Lannog only in the 13th century.
