The bank and inner ditch in the south western quadrant of the henge. Seen from the path from the car park to the village. Concrete markers indicate where some of the circle of stones are missing.
Avebury henge consists of an earth bank, an internal ditch and one large and two small stone circles within the bank. A village lies within the stone circle. Avebury is a Scheduled Ancient Monument and, with Stonehenge, is part of a World Heritage Site. There is much detail at: Link and at: Link
Wandering through the web looking for information on Avebury and the area around I found this excellent personal site http://www.avebury-web.co.uk/index.html which has lots of information and some fine photographs. It's well written and is worth taking a few minutes to browse through it if you have any interest in times past.