The 1837 Ordnance Survey map marks this location as ‘Site of Castle’, though no physical traces remain today. The building appears to have been demolished around 1826, after serving time as a military barracks. According to Richards’ 1691 map of the town, this was one of five castles in Mullingar, depicted as a small, square building on the north side of Main Street at the eastern edge of the settlement.

These castle structures were essentially fortified town houses, similar to examples that can still be seen in Ardee and Carlingford in County Louth. They were a common sight in 17th century Mullingar, as noted by traveller Piers in 1682, who observed that the town featured numerous ‘old fashionable castles’, some of which were being demolished to make way for more comfortable, modern houses. These buildings represented a transitional period in Irish urban architecture, when medieval defensive structures were gradually giving way to Georgian domestic buildings.

While subsequent Ordnance Survey maps show no indication of the castle at this location, the street name itself preserves the memory of this lost medieval structure. The castle’s precise footprint cannot be identified today, though historical maps suggest it stood roughly where Castle Street and Pearse Street now intersect, a spot that would have commanded views along the main thoroughfare of what was then the eastern boundary of the town.