Anyone who has been out walking or read about someone who's been out walking and comes across signs of Megalithic activity is welcome to post their thoughts. If interesting enough, the walk will be added to the Megalithic Walks section. Routes don't have to be in the British Isles.
Some people seem convinced that the oldest megaliths are in Brittany, closely followed by the Channel Islands. Since stones can't be dated, such claims are presumably made in order to support a particular theory. There are several theories doing the rounds, I've read that the oldest megaliths are in north Africa but again I wonder how they know this.
I've also read claims that megaliths are mainly sited along coasts and rivers... though no-one knows how many there used to be; several megalithic sites have disappeared, judging by the descriptions of relatively modern antiquarians like Camden, Stukeley et al. Keep your eyes peeled if you go on a walk!