The area takes its name from the eponymous Castle Magner, a Norman-era tower house which is located approximately 500 metres (1,600 ft) east of the village itself on the eastern boundary of Castlemagner townland. Owned by a Richard Magner during the Irish Rebellion of 1641, the tower house was largely destroyed in the late 16th century.[3][4] The lands surrounding Castle Magner were confiscated during the Cromwellian conquest of Ireland.[5] The castle is largely in ruin, though the stair turret and parts of the surrounding bawn wall remain.[3]
Close to the castle is Saint Bridget's Church, a disused but largely extant Church of Ireland church.[6] While the church itself was built in the early 19th century, the surrounding cemetery contains gravestones which are dated from the 18th century and earlier.[7]
A nearby holy well, also dedicated to Saint Bridget, is covered by a carved stone surround including an 18th-century inscription and a carving, sometimes claimed to be a Sheela na gig.[8][9][10]
Castlemagner's Roman Catholic church, which is dedicated to Saint Mary and was built c.1880, is located within the village itself.[11] There is a shrine to Edel Quinn, a local lay missionary, within the church grounds.[12]
^Charles Smith (1815). The Ancient and Present State of the County and City of Cork, Volume 1. J. Connor. p. 296. About two miles to the N. of Clonmene [Banteer], is Castle-Magner [..] In the rebellion of 1641, this castle belonged to Richard Magner, agent for the Irish inhabitants of Orrery and Kilmore
^Samuel Lewis (1837). "Castle-Magner". A Topographical Dictionary of Ireland. Castle-Magner, a parish [..] derives its name from the family of Magner, to whom this part of the country formerly belonged, and who erected a castle here, which was forfeited during the [Cromwellian] protectorate
^"The Journal of the Royal Society of Antiquaries of Ireland". 67. Royal Society of Antiquaries of Ireland. 1937: 180. That such [Sheela na gig] figures, though in a more restrained style, might be carved in all sincerity even later, is shown by the example at St. Bridget's Well, Castlemagner [..] It is carved by the door of the well, and [..] dated by Du Noyer to the seventeenth century{{cite journal}}: Cite journal requires |journal= (help)