Once you reach the summit of Knocknarea the size of this monster cairn hits you. It is obviously big, because you can see it for miles, but it is (see fig. really) big!
The ruins of the orbital passage tombs make this a centre to be compared with Newgrange (County Meath) and Knowth (County Meath), which also had smaller mounds built around it. Obviously, this also points to Maeve's Cairn being a passage tomb too, but as it's never been opened up nobody know for sure.
As the name suggests this cairn is rumoured to be the burial place of Queen Maeve.
There are two huge stones set diametrically opposite each other at the base of the cairn. One of these looks like a placed flag stone, but the other is a wonderful proto-altar type block - to me it is this stone that is the special thing up here. It is said that a line drawn through these two stones passes over the nearby mountain of Croghan, which has a curious rock-cut passage grave on its peak, which yielded a Carbon 14 date of around 5000bce.
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.