Castletown is situated in the civil parish of Abbeygormacan, barony of Longford Co Galway. It is bounded on the north by Liscoyle, on the east by Drimatubber, on the west by Kilbride and on the south by Cormuckorague.
O’Donovan’s Field Name Books gives 2 other spellings of this townland: Castletowne and Baile an Caisleain.
Down Survey map shows that this townland under the name ‘Cormake Oge’ was owned by John Blake FitzRobert, a catholic in 1641. It was owned in 1670 by Nicolas O’Hayn, a catholic. It states that there were 99 plantation acres of profitable land and 99 plantation acres of forfeited land.
No information on Castletown townland can be found from 1901 or 1911 census.