Stonehenge’s sarsens, of which the largest weighs more than 40 tons and rises 24 feet, were likely sourced from quarries 25 miles north of Salisbury Plain and transported with the help of sledges and ropes; they may even have already been scattered in the immediate vicinity when the monument’s Neolithic architects first broke ground there. The smaller bluestones, on the other hand, have been traced all the way to the Preseli Hills in Wales, some 200 miles away from Stonehenge. How, then, did prehistoric builders without sophisticated tools or engineering haul these boulders, which weigh up to 4 tons, over such a great distance?