Compared with the nearby tomb at Castlehill 1 (County Mayo), this seems quite large, but this is because there is no cairn left to hide the side stones.
There is some double walling left and the roofstones are still in place, but these rest on top of a fill of cairn rubble. The sides are formed by three slabs, each 1m square and the gallery is 1.5m wide.
Built into a ruined building on the opposite side of the road is what could have been a standing stone before it was utilised as a lintel above the fireplace.
In wedge tombs and court tombs the burial compartment is known as a gallery and collectively wedge and court tombs are called classified as 'gallery graves'. This is because the inner area is long and narrow, i.e. bascially rectangular, in plan.
In court tombs the gallery is usually divided into two or more chambers by jambs. Wedge tombs are segmented by sill stones, as are a few court tombs.
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.