Anglesey is beautiful and stuffed with ancient stones.
Bryn Celli Ddu, is a must I would say. http://www.megalithic.co.uk/article.php?sid=24
We went to Branwens grave which is on a spectacular headland but is blocked with concrete and unsightly railings.
There is loads more info on megalithic .co.uk
We also went to LLynon MIll and Iron Age settlement ( I just love roundhouses)
Amlwch has a lovely little harbour and info about the copper industry.
The scenery is wonderful in general but take good waterproofs!
I'm now wondering how soon I can go there again,
Have a great time!