Generally speaking Ireland is blessedly free of signs telling you not to fall over cliffs or trip over rocks, but if you are going to do it, you might as well go completely over the top.
The gently sloping margins of the Poulaphuca Reservoir (or Blessington Lakes as it is more romantically known, at least to Anglo-Saxon listeners) keep their dangers well hidden, and there are some pleasant walks to be had here for those prepared to live life on the edge.
This part of the Liffey valley was flooded in 1940 to create a water supply for Dublin and to drive the Poulaphuca hydro-electric power station. These days it also it offers all the usual water pursuits such as fishing, sailing, windsurfing, boating, leisure cruising and canoeing, and there are, or at least were, regular boat trips aboard the MV Blessington for those less energetic.
A short walk from the centre of Blessington village lie the gaunt remains of Burgage Castle and Church (map).
Already in ruins when the valley was flooded, the slowly collapsing tower-house and some fragments of the church are all that remain of what was once a wealthy pre-Norman ecclesiastical site of Burgage More. It became a borough in the 13th Century but appears to have been abandoned by in the early 14th. A sad spot.