Marked as a semicircular feature on the 3rd edition Ordnance Survey 6-inch map, this archaeological site has left no visible trace for modern visitors to discover. Its location, overlooking one of Donegal's most beautiful stretches of sand, suggests it may have served as a strategic vantage point for those who built it centuries ago.

The enclosure at Rossnowlagh Upper, also known as Crockahany, represents one of many lost archaeological features documented across County Donegal. While the exact purpose and date of this particular site remain uncertain, such enclosures typically served various functions throughout Irish history; they might have been defensive structures, livestock pens, or ceremonial spaces. The semicircular shape noted by early surveyors offers a tantalising clue to its original form, though without excavation, its true nature remains a mystery.

This information comes from the comprehensive Archaeological Survey of County Donegal, compiled in 1983 by Brian Lacey and his team of researchers. Their work catalogued field antiquities spanning from the Mesolithic Period through to the 17th century, preserving vital records of sites like this one that have since disappeared. Though the physical remains at Rossnowlagh have been lost to time and the elements, their documentation ensures that this piece of Donegal's ancient heritage isn't entirely forgotten.