Who, Why and How
Well, I guess we'll never really know who built the various phases of Stonehenge, bluestone henge or wood henge. We have some interesting theories here - did they come from Wales first and them moved up from Avebury?
The question of why really gets the juices flowing - there are endless theories. I like the totemic angle and the sense of evolution over many hundreds of years. I also believe that the meaning of he site probably changed more than once as the culture evolved.
How the stones were moved is interesting. Several ideas presented, but to my mind none of them cover all of the problems that would have been encountered. Maybe a mix of several different techniques were used to overcome different obstacles.