There are quite a few photos of Cavehill some dating back to the middle of the 19th Century. The earliest I could find is from the National Library of Ireland collection. It is not labeled as being of the Cave Hill but there is little doubt it is an image of the lowest cave. I notice the lichen visible on the pic is similar to that which can be seen near the area today. The fence is similar to one shown lower down in a print published in John Gray's booklet 'The Great Cave Hill Right of Way Case'. The photo is dated 1860 - 1890 - from the clothing I would put it at the lower of these dates.
The second photo again from the National Library of Ireland archives is from the 1880s -1914 or so and shows a group of walkers at the entrance to the first cave. The immediate area hasn't changed much in the intervening century or so. The big change is in the view over what is now Newtownabbey. Where once was farmland is now built up with housing and split by the M2 motorway.
