This is a massive hill-fort, im not sure of the size on top but its huge. The top of the hill has 3 stones lying around, one of them seems to have 3 cupmarks. The bank and ditch itself is massive and covered with scrub and so it is hard to get a good look at it. I know they say that this is a henge like construction and not used for defense but this bank would still be useful for defending id say. This site seemingly has been reused a number of times and evidence of timber structures were found on it. They were probably used for ritual use and seemingly a lot of animal bones were found on the hill which suggests feasting.
The views from it are magnificant, into wicklow, carlow, kildare and probably laois and offaly.
I came from Old Kilcullen and turned right out onto the main road N78 going back towards Dublin, where the road widens there is a spot to safely pull in about 100 yards after from the last house on left. There is a bit of a gate to hope with a sign saying that "this is a farm etc no liability". Then just walled up the hill. Lot of sheep in the fields at the moment so its safe enough. There were a few cows within the bank could be a bit unpredictable this time of year.