Stone Circles

I don’t know why they fascinate me, but they do. Perhaps the most well known Stone Circle is Stonehenge. A large number of Stone Circles are located in Europe. None are located in what is now the United States of America. What was their purpose? Were they ancient observatories? Were they ancient burial sites? Why are they limited to certain geographical locations in the world?Who were the builders of the stone circles? What secrets do they hold? What can the stone circles teach us today?