Researchers cannot unequivocally state how Stonehenge was built, though theories abound about its construction. The greatest part of the mystery is how bluestones were transported from a quarry in Wales to the Salisbury Plain where Stonehenge rests, a total travel distance of 250 miles.
Stonehenge was built with an outer ring of sarcen stones, which were mined near Salisbury Plain, but bluestone was used to form the inner ring. The closest source of bluestone is found in the Presili mountains in southwest Wales, a linear distance of 140 miles, but a total hauling distance of 250 miles when considering the likely means the builders used to get the bluestones to the construction site.
One of the most accepted theories is that the stones were rolled on huge logs to the river, floated down river in baskets or on rafts, then re-loaded on rollers for the final segment of the journey. Though the method sounds relatively simple in theory, such a task would have required thousands of men and well-coordinated logistics. Because it was such an enormous undertaking to transport the bluestones, most historians and scientists believe that those particular stones must have had great importance to the overall purpose of Stonehenge.
Though a similar structure could be built in very little time with modern construction equipment, it is estimated that it took over four centuries to finish the entire grouping of stones. Not only did it take a wondrous feat of engineering to haul the stones, but to also raise the pieces, each weighing hundreds of tons, into place.