A sign on the A841 just over a mile south of Blackwaterfoot points visitors inland to "Kirkpatrick Cashel", and just behind the sign a car park at the start of a farm track gives you somewhere convenient to leave your car as you set off on foot to look for the Cashel.
It is perhaps worth saying up front that you won't find one. A cashel is a name given, usually in Ireland, to a type of site used by early monastic communities. When the site at Kirkpatrick was first excavated in 1909 the archaeologist mistook what he found for a cashel. It is only quite recently that this interpretation has been overturned in favour of a dun, or fortified farmstead, built some 1800 years ago, to which someone has later added extra features which blur the picture.
You reach Kilpatrick Dun by following black and white marker posts up the hillside to the south east. The roadside direction sign gives the distance as half a mile and the map confirms its accuracy, but on even a mild climb (the dun is about 200ft higher than your starting point) to an unknown destination, the distance to the dun seems considerably longer.
If it is any consolation, the distance back to your car from the dun seems correspondingly shorter. Only at two places on the walk to the dun is there any doubt about the direction you should follow. The first is very near the start of the walk, where you need to turn right up a track and away from the main farm access road. The second is not far below the dun itself, where you have an unsigned choice of two paths that head off at different angles: keep left.
Kirkpatrick Dun occupied a magnificent location with views that extend over much of the west side of Arran, and which are especially good towards Blackwaterfoot. These views make the walk to the dun worthwhile in their own right.
The steady encroachment of vegetation over the centuries and the re-use of stone mean that what you are looking at when you reach the dun is at first far from clear. Gradually, however, it is possible to make out two distinct circles on the ground. The smaller is the footprint of the dun itself, a fortified farmstead which would once have stood to a sufficient height to have deterred casual attackers. With the eye of faith you can actually follow what seem to be the remains of the base of the outer walls of the dun on the ground. Identification of what was actually here is confused by a second, much larger, circle which can also be traced on the ground. This encloses nearly a hectare of land and is now thought to be a turf bank added during a period of later occupation of the dun (many duns saw repeated use right up to the medieval period and beyond) to enclose land associated with it.
It is, finally, worth noting one additional point of possible confusion to be avoided. The excellent information board beside the site correctly identified it as a dun. But don't be deceived by its opening words: "In front of you is a thick-walled dun..." The board has been erected the wrong way round, and as you read it, the dun is behind you.