Greadal Fhinn is a neolithic cairn of the Hebridean type, with a smaller central cist chamber (right) and larger passage chamber (left), both once covered in a mounded cairn structure of about 22m diameter.
That the cairn is known as Greadal Fhinn is confusing. Local lore has it that the ‘Fhinn’ refers to a Viking chieftain Ketill Flatnefr of Raumsal, known on the west coast as Caithil Fin. In 888AD he fled Norway and, according to the Sagas, settled on the west coast of Scotland, where he later died. The suggestion seems to be that he was buried here.
Similar large local cairns are at Camas nan Geall and Swordle. All have in common that they are set near but back from the coast, and have associated settlements.
Historic Environment Scotland's designation is here and the Kilchoan Diary history of Ormsaigmore is here.