Irish grid reference: O1020 2161. The holy well is located to the east of the Upper Bohernabreen Lake (reservoir) along a path which winds through fields that are often muddy and rough some 250 yards to the north of Kilmesantan, in the Glenasmole Valley, 4 miles south of Tallaght. Originally dedicated to a Celtic bishop called St Santan or Sentan, but later re-dedicated to St Anne. Today the well is still a place of pilgrimage to many local people; it has a rough-walled granite surround and an arched roof with a large ash tree leaning over it, making it hard to find at the best of times. There also is a figurine of St Anne standing inside what looks like a caged structure, probably so that she doesn’t get nicked!
The well was always visited on St Anne’s feast-day 26th July for its curative properties; the water was known to be clear and cold coming from deep in the ground. It was regarded as a cure for soreness of the eyes and stomach aches etc – bottles of the water being taken away by pilgrims to be handed out amongst their families no doubt. The water from the well is said to run into the Upper Bohernabreen reservoir a short distance to the west.
250 yards to the south at Glassamucky is the old graveyard of Kilmesantan (O1015 2142) with a ruined church inside the square-shaped low walls. Originally the 13th century church which stands on the site of an earlier Celtic church, was dedicated to a St Santan, Sanctan or Sentan, a 5th century Celtic bishop and son of the king of Britain (Coel of Strathclyde?), according to the Book of Leinster, but who was also a missionary at Kirksantan, Isle of Man, and in north Wales at Llansannan, near Llangernyw, where he has a church dedication, and also at Llantrisant, Anglesey.
Only the south-east wall still stands, the rest of the building consists of foundation stones in a rectangular pattern among the gravestones. In more recent times the church was re-dedicated to St Anne. We know that the nave measured 16 by 36 feet, the chancel was 12 feet long and the walls a staggering 3 foot thick. Beside the gate there is a stone font, now broken at the back, that is over 2 foot high and 3 foot square, with a depth of nearly 1 foot. This was probably the font from the church and could be quite old. A crude Celtic stone cross was found in the graveyard some while back; it now resides in the National Museum of Ireland at Dublin.