This fort gets its name from Ængus, one of the sons of Hua Môr, a famous chieftain in our pre-Christian history. It is situated at the very edge of the highest portion of the sea-wall on the southern shore of the Great Isle of Aran. Nothing finer can be imagined either for strength or grandeur than the site of this fort. At this point the cliff rises from the waves 300 feet in perpendicular height. To the north and west stretches out the ultimate ocean; on the south the bold promontories of Clare go out to meet the advancing waves; and further on can be discerned in the dim distance Cuchullin's Leap (now called Loop Head), and Brandon Mountain in Kerry, faintly traceable against the sky. All around there is the naked limestone rock, and scarcely discernible from the rock are the giant walls that once formed the last refuge of the ancient Belgic race in Ireland. The plan of Dun Ængus can be much better understood since the recent restoration effected by the Board of Works. This wonderful fort occupies an angle of the cliff, and in outline is semi-elliptical, with the diameter resting on the edge of the cliff, which itself formed a natural and impregnable wall on the sea side. The fort consists of a triple line of defence, and thus included a triple area rudely concentric. The wall of the inmost area is eighteen feet high, and about eight feet thick. It was built without cement of any kind; but really consists of two separate walls built close together of stones moderate in size, but carefully laid in horizontal positions. This inner wall surrounds a bare rocky floor, now covered with green turf, 142 feet along the cliff's edge, and about 150 feet in depth from the cliff to the furthest extremity. This inner wall had an entrance some 3 feet 4 ins. wide, and quite perfect when visited by John O'Donovan in 1839; but its lintel has since been thrown down, and the margins broken. It has, however, been lately restored by the Board of Works. The middle wall is at a considerable distance from the inner enclosure, in some places more than 200 feet, but on the north-western corner, where it approaches close to the cliff, it is not more than 22 feet from the inner wall. Outside of this second wall there is a very extraordinary _cheveaux de-frize_, consisting of large sharp stones set upright, so sharp and so closely set that even to this day it is impossible for man or beast to make their way through them, even with the greatest caution, without cut shins, if nothing worse should happen. We have ourselves tried the experiment, and we did not escape scathless. Nothing more efficacious to break the ranks of an advancing foe, whether horse or foot, could possibly have been devised. Beyond this _cheveaux-de-frize_ there are the remains of a third wall, which enclosed a very considerable space, and terminates, like the other two, on the very edge of the stupendous cliffs.