The aisled St. Mary's Church of square ground plan whose lateral walls have been preserved almost to their original height. The size of the church (11x 24 m) indicates a large population of the nearby castrum erecting this edifice in the 5th - 6th centuries.
The altar area is two steps higher and is divided from the church nave by a partly preserved triumphal arch. The altar basis is preserved in situ. The atrium of the basilica holds a small collection of stone monuments, exhibiting, among other, church finds, transennae, stone window grids.
The front part of the basilica and around it was the site of an Early Christian cemetery 300 m long, stretching as far as the southeastern corner of the castrum.
The beginning of the 9th century saw the renovation of numerous churches, among them St. Mary's. It was refurbished with new stone furnishing bearing the recognizable interlace pattern. The large pagan population must have caused missionary activities carried out by the Benedictines from the many monasteries. If not earlier, this is when the Benedictine monastery was founded stretching north and south of the church.
In the 13th century the basilica belonged to the Templars, but when their order was abolished in 1312, life in the monastery faded away.
Near this church, a smaller aisleless church dedicated to St. Peter was built whose floor was decorated by a tricolored mosaic.
References:Saint-Georges de Boscherville Abbey is a former Benedictine abbey. It was founded in about 1113 by Guillaume de Tancarville on the site of an earlier establishment of secular canons and settled by monks from the Abbey of Saint-Evroul. The abbey church made of Caumont stone was erected from 1113 to 1140. The Norman builders aimed to have very well-lit naves and they did this by means of tall, large windows, initially made possible by a wooden ceiling, which prevented uplift, although this was replaced by a Gothic vault in the 13th century. The chapter room was built after the abbey church and dates from the last quarter of the 12th century.
The arrival of the Maurist monks in 1659, after the disasters of the Wars of Religion, helped to get the abbey back on a firmer spiritual, architectural and economic footing. They erected a large monastic building one wing of which fitted tightly around the chapter house (which was otherwise left as it was).