Furness contains a 'calendar stone' dating to . The church is in the grounds of Furness House, owned by
Patrick Guinness. The church is Early Christian () and it was extended by the Normans in 1210. On the
Norman conquest of Ireland after 1169, lands in Kildare were assigned to
Adam de Hereford who in turn bequeathed them to the
Abbey of St Thomas the Martyr, Dublin. This monastery extended the church in 1210, allowing a roof for the congregation. The name derives from the Irish
fornocht, meaning "bare hill." In the 1530s the monastery was
dissolved by the Crown and its land at Furness was bought by the Ashe family, merchants in
Naas. The church has doors and windows edged with
tufa, a form of limestone favoured by Cistercians in Europe from the 12th century onward. The exception is a
leper window, usually blocked up now in older churches. At some point the church burned down and was abandoned. Despite being Protestant, the Nevill family owning the land allowed local Catholics to continue to bury their dead around the church alongside their ancestors. One gravestone from the early 18th century reads
IHS, signifying a Catholic burial. Burials stopped in the 1840s when the then owners built a wall around the estate as a famine relief measure. A standing stone is located north-northeast of the church. ==References==