The construction of the church in Portskewett began in the Norman period, perhaps in the twelfth or thirteenth century. At the beginning of the fourteenth century, a chancel was added, and in the sixteenth century a tower. Victorian renovations from the 19th century did not bring much changes, only in 1818 a gallery (matroneum) was erected in the western part of the church.
The church was built of gray and red limestone and yellow sandstone used for decorative finishing. The building consists of an aisleless, rectangular nave, and a narrower and shorter, rectangular chancel, which was added to the nave in the fourteenth century. From the west the church has a tower, and the southern entrance to the nave precedes the porch. The original entrance is also unusually on the north side. The tower was topped with battlement and equipped with a communication turret on the north-east side.
Website britishlistedbuildings.co.uk, Church of St Mary A Grade I Listed Building in Portskewett, Monmouthshire.