The Devenish high cross is rather unusual. The head has the most odd looking top I think I will ever see. It is dated to the 15th Century.
Next to it is a square foundation, which is thought to be the original cross base. Immediately behind this setting is a large grave slab with a worn effigy carved in relief. Some have recently suggested that this may be a Sheela-na-Gig. I couldn't see it myself, but it does remind me of the carved slab at Jamestown Cross (County Dublin).
This is an explanation of (and a bit of a disclaimer for) the coordinates I provide.
Where a GPS figure is given this is the master for all other coordinates. According to my Garmin these are quite accurate.
Where there is no GPS figure the 6 figure grid reference is master for the others. This may not be very accurate as it could have come from the OS maps and could have been read by eye. Consequently, all other cordinates are going to have inaccuracies.
The calculation of Longitude and Latitude uses an algorithm that is not 100% accurate. The long/lat figures are used as a basis for calculating the UTM & ITM coordinates. Consequently, UTM & ITM coordinates are slightly out.
UTM is a global coordinate system - Universal Transverse Mercator - that is at the core of the GPS system.
ITM is the new coordinate system - Irish Transverse Mercator - that is more accurate and more GPS friendly than the Irish Grid Reference system. This will be used on the next generation of Irish OS maps.