The ruined church at Kill o' the Grange in County Dublin, Ireland is among the oldest ecclesiastical remains in the county. The site was the location of a monastic cell (cill) dedicated to Saint Fintan which dated back to the early Christian era in Ireland - between 500 and 800 AD. In the grounds of a nearby house, there is a bullaun stone - a stone with hollows on the surface which may well date from the Bronze Age.
The area was originally called Clonkeen, from the Irish Cluain Caoin meaning Beautiful Meadow. In 1088 AD a local chieftain, Donogh Son of Fat Donald, bestowed the Kill of Clonkeen and its extensive surrounding lands on the Priory of the Holy Trinity in Dublin. The Priory was in the charge of the Augustinian order, who later built Christ Church Cathedral on land adjoining their priory.
The stone church building has been dated by archaeologists from this period, replacing an earlier mud and wattle walled, thatched roofed building. During this time also the church became a parish church supported by tithes levied on the parishioners. The property was recorded unable to bear taxation in 1294 although it was valued at £18 8s 4d in 1306.
With the Reformation in 1539, the Priory of the Holy Trinity escaped suppression by submitting to King Henry VIII. The Prior became Dean of Christ Church Cathedral and was assigned the grange or farm lands at Clonkeen as his portion. The area became known as the Dean's Grange.
The church was in good repair in 1615 but by 1630 had lost its roof to recent storms and the congregation was down to only twenty-four souls. The church was not rebuilt and the parish was subsequently amalgamated with Monkstown.
The churchyard, which was used for burials up to the First World War, is currently in the care of Dun Laoghaire-Rathdown County Council. The south wall of the churchyard was taken down in 2003 as it was in a dangerous condition and was rebuilt in 2009.
I am indebted for much of this information Ken Finlay's The most complete history of Dublin on the Web and to Liam Clare's article in the Foxrock Parish eZine.