The example at Garrysallagh in County Cavan takes the same basic logic and transplants it inland, positioning itself above a river just where that watercourse meets the eastern shore of Lough Sheelin. Here, the natural geography of river and lakeshore replaces the cliff and the tide, and what remains of the fort survives not as visible earthworks but as cropmarks, the faint signatures that buried ditches leave in growing crops during dry summers, legible only from the air.

Aerial photographs reveal three widely spaced curved fosses, the term for defensive ditches, tracing the outline of an enclosure on this riverine promontory. Three concentric or parallel lines of defence is a substantial investment, suggesting the site was considered worth serious effort by whoever built and used it. The photographs place the enclosure roughly two hundred metres east of where the river drains into Lough Sheelin, a location that would have offered both a natural boundary on at least one side and a commanding view along the water. The broader Lough Sheelin basin sits in a drumlin landscape shaped by glacial activity, and the kind of elevated ground that makes a defensible promontory here tends to be a drumlin spur or ridge rather than a coastal cliff. The date of the fort is not known from the available evidence, though inland promontory forts as a class are generally associated with the Iron Age or early medieval period in Ireland.

Because the site is known primarily through aerial evidence, there is little to see on the ground without specialist knowledge of how to read a landscape for the subtle undulations that might betray buried features. The area around the river mouth and the eastern shore of Lough Sheelin is worth approaching with that context in mind, understanding that what looks like an ordinary field may sit directly above a carefully planned and multiply defended enclosure that has been quietly present in the soil for well over a thousand years.