Parking at G 88002 36470 A I was confused to see such a sign as OS16 2nd Edition shows that this is part of O Donnell's Rock walk. Unfortunately this walk, although identified on the map, has little physical sign in reality. As luck would have it a local farmer explained that the sign was from a bygone landowner and the present landowners have no problem with walkers (no mention of horses)
Accessing the summit is by this track to top and through some turf cutting areas, although on a flattish area a higher mound is evident which I took as the summit. As this area is popular with paragliders who normally drive to the top from the South side, take a tar and gravel track past masts and park at a forest entrance ( G 87918 34895 B); from here it is a relatively short hop to the summit with little ascent. Linkback: https://mountainviews.ie/summit/1133/comment/16076/

Interesting to read the comments on this hill from previous years. The no walkers sign pictured by sandman is no longer in evidence but the O'Donnell's Rock walk marked on the OS map (I used the OSNI Discovery sheet 26, and the walk is also marked and similarly named on that) is not in evidence either: no signs, walking posts, nothing I could see. Nevertheless, the track is there and easily followable. The only gate to pass was closed but not locked and there are no fence crossings, so access seems not to be an issue. It is evidently a bog track and there is a small amount of turf on the broad summit, so it is still being worked to some extent.

I walked from Manorhamilton town centre, following a bit of greenway and a quiet back road before turning left up the track at the point noted by sandman through a hazel wood to the extensive and boggily undulating summit plateau. It was about 15 km there and back including some wandering around the top. The summit (600 boggy metres off the track - good boots recommended for this part) is a bit of a non-event but it is worth going to the top of O'Donnell's Rock itself (just a couple of minutes' walk off the track) for the best view over Manorhamilton and its surrounds. Just below the rock is a ruined house, seemingly the home of the eponymous O'Donnells from what I have read online.

There are megalithic tombs marked further north on the summit area at around G899 368 C but I didn't get that far. OSNI Discovery 26 also indicates tracks leading off this side of the hill back to Manor but with a few potential tracks criss-crossing the summit and no signage, I retraced my steps and descended to the west.

I enjoyed this walk in the heart of the Leitrim glens immensely, though it was one of those golden autumn mornings when being on any hill is pretty good. I did not meet a single person on the hill. Linkback: https://mountainviews.ie/summit/1133/comment/24298/