I was there in May of this year and was blown away by it all (metaphorically speaking). Well yes, and physically. Was lucky enough to spend some time with Margaret Curtis who gave us some insights we never would have gained otherwise. She said Callanish is not a World Heritage Site and is unlikely to be in the foreseeable future because of strict Free Presbyterian adherence on Lewis. Odd really when you think of how big the Callanish site is with both sites II and III all within sight of each other - it has to be easily as important (if not more so) than Stonehenge.
Margaret Curtis is in her early seventies now and has my greatest respect, not just for her knowledge but for her calm acceptance of her life without her late husband Ron Curtis. I'd love to see it happen for her as much as anything else.