The stone is supposed to come from South Wales I believe and yes they wer supposed to have dragged them to stone heng, but why that place I dont think anyone really knows.
One theory is that they did not lift the stones. Rather built huge mounds of earth, dug big holes in the mound , pulled the stones up to the top and tipped them into the holes standing upright. Then they got the cross stones, laid them in place ontop of the upstanding stones, then dug the earth mound away and there you have it.