Known locally as Rinnaraw Cashel, this circular settlement wasn't recorded on early maps until 1905, though excavations in the late 1980s and early 1990s revealed it to be a fascinating glimpse into 9th-century coastal life in Donegal.

The excavations, led by Professor Tom Fanning and later completed by Michelle Comber, uncovered the remnants of a small, self-sufficient community. At the heart of the 25-metre-wide enclosure stood a subrectangular house with distinctively rounded corners, reminiscent of Norse dwellings found in Orkney. The western half housed this dwelling, whilst the eastern section served as an open yard where ironworking took place. A fire pit cut into the bedrock, surrounded by slag, ore fragments, and furnace bottoms, shows that both smelting and smithing happened on site. Shell middens packed with limpets and periwinkles accumulated beside the house, whilst animal bones reveal a diet of cattle, sheep, pig, and the occasional seal, supplemented by cod and ling from the nearby waters.

The artefacts paint a picture of modest, industrious inhabitants who ground their grain with rotary querns, mended their tools on whetstones, and crafted simple implements from flint and bone. Particularly intriguing are the pottery sherds; all identified as souterrain ware, a type strongly associated with northeast Ulster, featuring handmade, burnished black vessels. Radiocarbon dating suggests the main occupation occurred during the 9th century, with possible reuse in the 11th century or later. The timing is significant, coinciding with documented Scandinavian activity in this part of Donegal, and the architectural similarities to Norse buildings, along with fragments of possible Scottish-style trough querns, hint at broader cultural connections across the Irish Sea during this turbulent period.