Slieve Anierin has a hidden altar in its SE cliff face. Behind a rock crag split off from the main cliff face is a small but remarkable paved area complete with altar, all using rock from the surrounding area. My route visits this before moving on to find one of the smallest Trig pillars in Ireland at the summit of Slieve Anierin. (it's about 2 inches high!). The route continues to Knockacullion before descending some very steep ground on the return. The route starts by following a good track into the bog below Slieve Anierin. However my route involves some very tiring pushing through reeds, rushes and tall grass on the return leg on the section below Knockacullion heading for the good bog track. NOTE - my descent to the bog after leaving Knockacullion involves negotiating very steep ground and cliffs. My route shows a way to walk down, but extreme care is required to find this route amid the surrounding cliffs and steep ground. If in doubt abandon this section and simply retrace your route via Slieve Anierin back to the start.