Only a few of the original huge stones are still standing, so it's difficult to say more than Stonehenge consists of huge (twenty-five feet tall, twenty-plus ton) rocks that were put in place 2,000 to 5,000 years ago.

When did someone first notice a characteristic that connected the stars, the moon and the position of the sun, with the seasons? How was the information 'recorded' and passed from generation to generation?

Did two different groups of people (Stonehenge, and Carnac, France, separated by the English Channel), study the sky, come to the same conclusion, and use huge stones to build astrological installations? Or did members of one civilization cross the channel, and transplant the knowledge that must have taken many generations to perfect?

References we have read do not indicate a connection between Carnac's Avenues and the Great Circle at Stonehenge, but the use of huge stones, and the apparent astronomical purpose are certainly similar.