This is not an attraction that takes you hours to see, but it is fascinating. I would recommend you do your homework and learn about the circles before visiting, because I didn't see any information booth anywhere around the circles, and you may not get any knowledge on them unless you had a tour guide. As for Avebury itself well I was in Avebury for two hours and it was enough time to go wander the fields and see the stones and take photos, as well as to wander the village a bit and do a bit of shopping.
* A bit of knowledge to start you off... The stone circles were constructed around 2600BC, and hold a religious importance to pagens even tho the importance of the circles are not totally clear.
This review is the subjective opinion of a TravelPod member and not of TravelPod.com.