The destruction of.. Borough Walls, overhanging Nightingale Valley, revealed the construction of the walls. It had a triple rampart formed of loose stones, the principal rampart being run together with lime, so as to have a solid mass of concrete in the centre.
This had been produced by mixing the lime-stones with brushwood, which was set on fire, and then when heated, water was poured in, or the smouldering mass left open to the rain, and then fragments of stone cast in, so as to form by degrees a solid mass of concrete, which could not be dug through.
The whole was then banked up with earth and stones, and probably a palisade planted on the summit. All this has now been cleared away and we cannot but regret the loss of so interesting a structure. Hardly any trace of it remains.
From the Proceedings of the Bath Field Club, vol 5, p 4 (1885).
How many forts does one small area need? You have this site and Stokeleigh Camp on one side of the Avon Gorge, and Clifton Camp on the other. Burgh Walls has been transformed into Burwalls, a large house with gardens now owned by Bristol University. There are traces of the earthworks left: if you contacted the university they might let you look (they occasionally do tours).
The fort is mentioned in the Bath Field Club proceedings for 1877:
What shall we say of a building company which has lately consigned to utter destruction one of the most important and interesting historical monuments of this neighbourhood? I mean the camp on the Somerset side of the River Avon, called Bowre Walls, and opposite the camp on Clifton Down. This has been almost obliterated for the sake of the material of which the ramparts of the camp were composed, and which has been used in making roads! How much better to have preserved these ramparts entire, and have made them a part of the ornamental garden attached to the new villas erected on the heights over the Avon, and so associated the marks of ancient warfare with the elegancies of modern civilisation.
Surely it is necessary that some power should be given to prevent the monuments of past ages being wantonly destroyed, and we must be thankful that the subject has lately been brought under the consideration of Parliament.