Thor...have they ever figured out the purpose of the stones...I heard they made a recent discovery at Stonehenge but never heard any followup on the conclusion...I think it's better to let one's imagination run freely on the purpose.....
Jake there are a number of theories and it is hard to be absolutely certain of the purpose of stone circles. What is known is that they occur all over Europe and that they aren't all made of stone - some are made of wood (such as Woodhenge) and some similar monuments are marked by banks and ditches.
It is hard to argue against some sort of religious purpose with the stones marking a sacred space. Some stone circles (such as Stonehenge) seem to have links to the calendar (with the sun rising in alignment with a line of stones on certain days each year) - this could easily fit with the religious aspect. Other suggestions have been trading centres (stone circles sometimes occur in neutral areas between tribal territories) but no one is really sure.
Whatever their purpose I just love them!