Rosshall Gardens: view through tunnel. At this point, at the western corner of the walled garden that was built alongside the old house of Rosshill, there is what appears to be a large irregular mass of rock with a short tunnel through it. It is unlikely that any tunnelling was involved in its creation; more probably, the rough form of an arch was created, and then coated and built up with stone-like material to give the impression that it had been hewn from natural rock. The metal fence in the background is that of the old Rosshill, which later served as a boiler house.