Final answer:
Stonehenge was primarily constructed from sarsen sandstone for the outer circle and smaller bluestones for the inner circle, illustrating significant prehistoric engineering and transportation efforts.
Step-by-step explanation:
The primary materials used in the construction of Stonehenge were two types of stones. The outermost large circle is composed of sarsen stones, which is a form of sandstone, sourced from Marlborough Downs, approximately 29 kilometers away from Stonehenge. The inner circle contains smaller stones known as bluestones, believed to have been transported from a location in Wales, over 250 kilometers distant.
These works indicate the remarkable effort and engineering skills of the Neolithic people, with the largest sarsen stones weighing about 25 tons each. The bluestone stones weigh between two to four tons each, illustrating the monumental construction efforts of Neolithic societies.