UCD historian finds the Norman castle of Roebuck still standing under a Victorian building's plaster

O'Keeffe worked from what is still legible through later finishes. "The medieval features are still there. They're hidden under plaster but they can be made out," he said ^[6]. The corroborating evidence came from a painter. Gabriel Beranger visited the ruins around 1765 and recorded them in a series of watercolours ^[13]. "Beranger's depictions of the ruined castle are really fascinating," O'Keeffe said. "He captured the basic form of the building, as you would expect, but thankfully he also captured some of those small details, which are the clues needed to work out the building's structural history" ^[14]. The report does not say how much of the castle's fabric survives, or whether any of it was opened up for inspection ^[20].

"From the outside, the present building looks to be entirely Victorian. Inside, though, the walls of the old castle are preserved," O'Keeffe said ^[5]. He credits the people who remodelled the property: "We are incredibly lucky that the Georgian and Victorian modernizers of the property simply built around the medieval castle rather than demolish it. And we are also lucky that they built very little else on the site. The courtyard at the back of the house today is actually the medieval castle courtyard!" ^[7]

Historical sources put the castle's construction within living memory of the Norman invasion of Ireland in 1169, with several alterations during the Middle Ages ^[9]. Take the oldest fabric at an early-13th-century date and the first build went up roughly 30 to 60 years after the invasion ^[18]. It guarded one of the approach roads into medieval Dublin ^[10]. Its occupants included a medieval Lord High Chancellor of Ireland and, according to tradition, the deposed James II, reputed to have stayed there in 1689 ^[11]. By the 18th century it was a ruin and was believed to have been cleared away in later redevelopment of the site ^[12]. Beranger therefore drew it around 550 years after the earliest parts were built ^[19].

The campus ranking is O'Keeffe's own claim and it rests on that early-13th-century date. "UCD can now claim to have the oldest standing building on any university campus in Ireland," he said ^[8]. The research is published in Archaeology Ireland magazine ^[3].

One identification is not a rate. Few medieval castles survive in south Dublin, and many were demolished in the 17th century with their stonework recycled into more comfortable residences ^[15]. "The passage of time has been unkind to the castles that were built across south Dublin in the Middle Ages," O'Keeffe said ^[17]. Roebuck came back because three things lined up: a documented ruin, an 18th-century artist who drew its details, and later owners who built around it. How often that combination occurs elsewhere is not something a single case can measure. "Lost buildings are lost historical records. They leave gaps in our knowledge," O'Keeffe said ^[16].