These Cornish men , camped on the western slopes of the highest hill in the vicinity of the Irene Station , built a rough stone fort to protect the railway line linking Johannesburg to Pretoria .
Thus the hill became known as Cornwall Hill .
These Cornish men , camped on the western slopes of the highest hill in the vicinity of the Irene Station , built a rough stone fort to protect the railway line linking Johannesburg to Pretoria , and thus the hill became known as Cornwall Hill .