A “dun” is a larger fortification, few and far between on the island of Ireland. We saw one on the Arran Islands, from the Iron Age, Dun Angus, Charles Fort, or Dún Chathail in Irish, is from historical ages.
A cannot tell from my slide show, but the walls are star shaped with many salients, giving more positions to defend the walls.
“Charles Fort” – wikipedia
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