I posted RockNicker's picture of Duddo stone circle because I thought that was limestone - but it's sandstone like the rest. Burl's quote for the usual material used to construct stone rows 'glacial erratics'. I know of no circles or menhirs that are 'granitic'. A better option is probably to look for a section of rock with these features that has been out of the elements for a large part of the last four thousand years or so.