Figsbury Ring Iron Age hill fort
On the face of it Figsbury Ring near Salisbury is just a standard univalate Iron Age hill fort, but once you’ve passed through the entrance there’s a near perfect circular ditch with what appear to be two causeways. Interestingly the two causeways appear to line up with Old Sarum which is a couple of miles further West. So I’m thinking, hang on a minute , this looks like a Neolithic causewayed enclosure? Not uncommon. Many hill forts started out like that. However there is little evidence from excavations by the Cunningtons in the 1920s to date it as a Causewayed Enclosure, so the other possibility might be that it was originally a Henge monument. Unfortunately nobody seems willing to verify this, so it remains a mystery.
the inner ditch
Old Sarum is just a few miles further West