Far fewer are aware that beneath its Victorian seafront and modern suburban spread lies a medieval planned town, complete with a Norman castle, a mill, and burgage plots, the long, narrow strips of land granted to settlers in exchange for rents and services, that date back to at least the thirteenth century. More striking still, a number of Roman burials have been discovered near the seafront, an unusual find in an Irish context, where Roman-period archaeology is rare and tends to prompt as many questions as it answers.

The town's medieval origins rest largely with one figure: Walter de Ridelesford, a Norman lord who received the manor of Bray before 1176. The settlement that grew under his tenure was divided by the Dargle River into two distinct parts, Little Bray to the north and Great Bray to the south, a division that still shapes the town's geography today. Around 1225, de Ridelesford granted a burgage described as lying "opposite my castle beyond the river" to St Mary's Abbey in Dublin, the earliest written reference to the town's burgage tenure and an indication that a functioning castle and nascent urban settlement were already in place. A mill operated below the castle as well, a practical anchor for any medieval community dependent on grain processing. The manor remained in de Ridelesford hands until 1280, when it was resigned to the Crown, closing the family's century-long association with the place.