Folklore

Poundbury Hillfort
Hillfort

On [one] side of Dorchester, on a steep bank overlooking the river Frome, is a single entrenchment called Poundbury (locally, “Pumbury”); it is an irregular quadrangle the longest side of which runs nearly parallel with the river and is more than 400 yards long, – the extreme width is about 150 yards. This is attributed by some to the Danes, and by others to the Romans, who are thought, with much probability, to have erected it when attacking or “observing” Maiden Castle..

Local folklore or just antiquarian speculation? hmm.

Remarks on Some Archaic Structures in Somersetshire and Dorsetshire.
A. L. Lewis
The Journal of the Anthropological Institute of Great Britain and Ireland, Vol. 11. (1882), pp. 117-122.