Monkstown ( - 'the town of the monk', formerly anglicised as Ballinvannegh) is a village in County Cork, Ireland, in the old barony of Kerrycurrihy. It lies 14 kilometres southeast of Cork city on the estuary of the River Lee, facing Great Island and looking onto Monkstown Bay.
The name of the village is said to derive from an early monastic site near to where Monkstown Castle now stands. Although no archaeological evidence has been found for the monastery, evidence has been found for early communal agricultural work in the area. A very early cemetery also exists near to the castle. Over time the name Baile an Mhanaigh/Monkstown overtook the old name Baile an Fealach (Foley's homestead), although the latter name persists in the name of a townland of the village: Ballyfouloo.
The castle, for which the town is famed, is in fact not a castle at all but a fortified tower house. It was constructed around 1636 by Anastasia ArchDeacon (née Gould) as a surprise gift for her husband, who was fighting with the Spanish Catholics in the continental wars of the time. As implausible legend has it, when John ArchDeacon's ship entered Monkstown bay, a cannonball was fired at the castle which was believed to house enemies. Anastasia ArchDeacon hired workers to come to Monkstown to build the castle. She housed the workers in accommodation built specially for them. She also provided them with food and clothing, but for a price. Once the workers had paid their rent and settled up their bills with her, it is said that the overall cost of the castle worked out at about four pence. The ArchDeacons are buried close by in the now overgrown graveyard.