Caisleáin Aircín (Arkyn Castle)
This is situated on the shore side of the road before Cill Éinne pier and village. The site probably marked the location of an O Brien stronghold. English occupation in the 1580s, however, saw the building of the castle. Following the arrival of Cromwell in the mid 17th century it was further fortified using the masonry from the nearby round tower and churches. Little remains of it today.