I'd recommend anyone interested in visiting Stonehenge to also make a stop at Avebury - there are many more stones there that you can walk around and touch (without getting into trouble!)
Also, Newgrange in Ireland is fantastically interesting. Burial mound (probably) whose chamber is illuminated by the rising sun each year around December 21.
> Stonehenge is to Avebury as a parish church is to a cathedral.