Chair of Kildare

This site isnt far from Kildare travelling north. It is on the Hill called Grange on a lower peak a little to the west. I dont know how old the mound is. It is quiet a big mound between 10m diameter and about 5m high. I was interested in it because of its place on the hills of the curragh plus the folklore/traditional name for the hill is the Chair of Kildare. Ive no idea why that is. The summit of Dunmurry hill also appears to have a mound on top but it is not marked on the OS map and so probably is just a trig point mound.