This is a small cluster of small huts. There are about 5 or so of them and some associated external walls. Each hut is only 3m or so across internally, with walls up to 1m thick (but there is soil piled around the walls so they were actually not that thick originally). You can make out gaps or indentations in the wall remains that would have been where posts were inserted, so the bits of wall that you can see were just foundations for a wooden structure.
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.