You can visit the four chambered cairns on the W of Bute in an easy three-hour walk. To avoid repitition under each site, I've put the location directions for all four here with cross references at the other sites.
Drive up the single track road from Ettrick Bay and park in the small car park at Glecknabae
To reach Glecknabae, walk back down the road a few hundred metres to a gate on the left. The cairn is visible in front of the gate.
For the other three sites, follow the farm track to Kilmichael. After about 10 minutes, a signposted track to the right leads to Carnbaan.
To visit the other two, continue up the farm track. As you reach the first farm buildings, St Michael's is in an unfenced field on the left.
For Glenvoidean, take the track on the right after the cottage just ahead of St Michael's.
Glenvoidean is arguably the most interesting of the four but it is gradually being taken over by a gorse bush which not only spoils the understanding of the site but spoils the view over the Kyles of Bute.
It is a Clyde cairn with one axial chamber (at its N end) and two lateral chambers (E and W).
For more detail, see the captions to the accompanying photographs.