"Wherever there is water and fertility in the Highlands, we generally find some remains of antiquity". A Tour through the Highlands of Scotland and the Hebride Isles in 1786. John Knox, James Thin, Edinburgh, 1975.
OK, so this isn't Orkney, or even Kilmartin Glen which is a bit too far from any of the anchorages round here to be easily visited, but there is still a lot of stuff around. I am not quite sure where archaeology ends and history begins, but who cares, this is what I think there is to see:
There are cup and ring markings at Sailean Mòr Kintyre as well as at Poll an Dùnain (Bishop's Bay), Loch Leven.
Duns are mostly iron age fortified structures on small hills — at Little Horseshoe Bay, Kerrera, Ardinamir Bay on Luing, at Bun an Leoib on Loch Scridain, and perhaps best at Castle Dounie near Crinan, but it is a bit of a walk.
On Canna you will find a Viking grave and a souterrain but they are both a walk from the main anchorage. And at Oitir Mhòr on Kerrera there is the almost invisible remains of the Cladh a’Bhearnaig monastery.
There are only two brochs — Vaul is the most complete but is something of a walk from the Gott Bay anchorage on Tiree, and there is a more ruined one on at Port Moluag on Lismore.
There is a very broken down but atmospheric chambered cairn on Loch Teacuis, and another at Port Donain, South East Mull.
There are separate pages for Castles, Ecclesiastical things and other Buildings of interest.