Three cromlechs in the same limestone plain add something to the mystery that overhangs all the rest. The first, at Lennan in Monaghan, is marked with a curious cryptic design, suggesting a clue, yet yielding none. There is a like script on the cromlech at Castlederg in Tyrone, if indeed the markings were ever the record of some thought to be remembered, and not mere ornament. The chambered cromlech of Lisbellaw in Fermanagh has like markings; they are too similar to be quite independent, yet almost too simple to contain a recorded thought.
We come once more to Donegal. On the hill-top of Beltaney, near Raphoe, there is a very massive circle formed of sixty-seven huge blocks. Here again the Stonehenge ring might be set up within the Irish circle, leaving an avenue eight paces wide all round it. The sacred fire was formerly kindled here to mark the birth of Spring. The name of the old festival of Beltane still lingers on the hill. At Culdaff in north Donegal, at the end of the Inishowen peninsula, stands another great stone circle, with which we must close our survey of these titanic monuments.
We have mentioned a few only among many; yet enough to show their presence everywhere throughout the land, in the valleys or on mountain summits, in the midst of pastures or on lonely and rugged isles. One group, as we have seen, cannot be younger than ten thousand years, and may be far older. The others may be well coeval. Their magnitude, their ordered ranks, their universal presence, are a startling revelation of the material powers of the men of that remote age; they are a testimony, not less wonderful, of the moral force which dedicated so much power to ideal ends. Finally, they are a monument to remind us how little we yet know of the real history of our race.