Badbury Rings is an impressive Iron Age Hill Fort, consisting of three near circular concentric rings around a low dome shaped hill.
It is often said that the term 'Hill Fort' is misleading, as the walls would not have provided much defence against a determined assault, and that they were more about proclaiming the status of the local chieftain, and impressing the neighbours.
Whilst self-agrandising politicians through the ages have always been keen to spend large amounts of public money and effort on useless projects in the name of defence, it is probably more useful to ask what use the locals made of the walls rather than speculating on the motives of their leaders.
Standing on the walls of Badbury Rings as the sun went down I tried to image them when they were first built. Then they would have been bare white chalk and would have been highly visible for miles around. Then I looked down at the beech avenue that lines the 18th century turnpike road from Wimborne to Blandford, and noted how it cut through the (probably Iron Age) field pattern. Then I looked up and picked out some familiar landmarks (the Charborough Tower, the radio masts on Bulbarrow, etc.)
How would people have found their way to places, I thought, in an age before roads (the great Roman networking innovation) when there were only local track ways and no signposts? The only way would be to go up on to some high ground, spot where your trying to get to, and head off in roughly the right general direction.
Shinning white walls, would be easily spotted from miles around, and as I see it, they would have proclaimed, "Here there is a market; here are iron workers, white smiths, specialist leather workers, etc. This is where the chief lives if you need to speak to him." In other words the walls were massive advertising banners. That would explain why the inhabitant chose to live on the exposed tops of hills instead of in the sheltered valleys.
It probably explains the Uffington White Horse as well.