Banner: Knocknarea at Sunset.
A picnic at the Greenan of Ailleach.
A picnic at the Greenan of Ailleach. Photo by W. A. Green © National Museums of Northern Ireland.

The Greenan of Ailleach

At the gateway to the Inishowen Penninsula, a great stone fort stands at the top of a high hill commanding a spectacular panorama across the surrounding landscape. This building is known as the Greenan of Ailleach and is said to have been built by the Dagda, the chief god of the Túatha Dé Danann, whose most famous residence is Newgrange. The Greenan (meaning Sunny Room) site was a fortress of the O'Neills, and commands the ancient routeway from Inishowen down into Donegal. It is close to the city of Derry, which was founded by St Columbkille.

The walls had collapsed and were rebuilt by the Bord of Works in the late 18th century. There are sets of steps leading to the ramparts on the top of the walls, and there are several internal rooms and passages in the walls. There is a well on the summit of the hill not far from the fort. It is an ideal site for a fortress, both for it's amazing panaromic views over the surrounding countryside and it's strategic command of sea and land routes.

The Greenan of Ailleach around 1900.
The Greenan of Ailleach around 1900.

On August 1st 1834 John O'Donovan wrote in his letter to Thomas Larcom:

I went on Thursday to see the ruin of the work of Rigriu and Garvan on the summit of a hill which derives its name from the building. It is amazingly interesting, but to me wonderfully puzzling! Is it possible that this can be the ruin of the celebrated palace of Aileach? A palace called Grianan i.e. Solarium (not the Temple of the Sun) for its splendour and Aileach (Ail-theach i.e. Stone House) from its being built of stone, where the three sons of Kermad were disputing about the sovereignty when they were visited by Ith, the brother of the Spanish Milesius? Can this be the palace called Grianan Ailich, which was destroyed by the O'Brien in 1101? Petrie says unquestionable.

I made every enquiry about it in its vicinity but could discover nothing; all the neighbours have lost their traditions and their old language. They could only tell me that the hill was called Grianan Gormley, and the ruin, the Ould Fourth. I have been very much disappointed, but I do not give it up yet.

Within the Greenan of Ailleach.
Within the Greenan of Ailleach. Photo by W. A. Green © National Museums of Northern Ireland.

Description of 'cave' at Greenan Hill from 1838.

At the base of the hill are several remarkable caves; which are considered by some antiquaries as associated with the ancient relies on the summit. Indeed, such occur in all parts of Ireland. Mr. Croker states that, in a circle of four miles "round Garranes," in the county of Cork, there are no fewer than thirteen of these "circular intrenchments" and he considers it "probable that these works were thrown up by the native Irish around their little wigwam settlements, as a defence against any sudden attack from an enemy or from wolves, and that subterranean chambers or cellars were formed for granaries, or as secure depositories in time of danger for their rude property*."

* The Cave at the base of Greenan Hill is now blocked up ; but we obtained some account of it from a gentleman—Andrew Ferguson, Esq., of Burt—by whom it was examined in 1838. It was known to be situated in a field forming part of the farm of John Alison, in the town-land of Speenogue, and parish of Burt.

It had been closed since A. D. 1785, in which year Mr. Ferguson recollected his having explored the several apartments. It was then discovered by a boy engaged in digging potatoes, whose spade forced itself between two of the flags which form the roof of the "cave." It remained open at that time for a few months, when it was again closed up by the then occupier of the farm.

The only person alive (in 1838) who had any idea of the exact locality of the building, was an old man, named William Dunn, who had lost his sight in early youth, but who remembered to have heard from his brother, that the subterraneous building was situated nearly opposite, but rather north of, a quartz stone in the wall, which bounds the field on the east side. The entrance was accordingly discovered.

The chamber into which we first obtained entrance—writes our informant—is somewhat dilapidated, and appears to consist of the original apartment of the building and of a sloping passage leading to it. It is much encumbered with loose clay and stones, and declines a good deal towards the lower extremity, where we were able to stand perfectly upright, although we were at first obliged to creep in on our hands and knees. The form of this chamber is oblong, or rather oval. On the arrival of lanterns we proceeded into the second apartment.

The well at the Greenan of Ailleach.
The well at the Greenan of Ailleach.

The passages between the first and second, as well as between the second and third apartments, resemble much the mouth of a large pipe, or the apertures (called in Ireland "kiln-logies," i.e. the eyes of the kiln) by which the fire is introduced into lime-kilns. These entrances are compactly built of large stones, and they both decline a little towards their lower extremity, a remark which is also applicable to all three apartments.

The second chamber is nearly circular, but approaches in form to the oval. Here, as in the other two apartments, the floor is of clay, and the walls are regularly built of large stones without mortar or cement of any kind, and incline perceptibly inwards at the top and bottom. In all these apartments the ceilings are composed of immense flags resting on the walls on either side, and smaller stones are advanced to support them in one or two instances where the flags were too short to cover the whole extent.

The stones employed in the construction of the building are the common schist of the country intermixed with whin-stones and some quartz. The walls were found by measurement to average about three feet in thickness. The passage between the second and third chambers branches off to the cast, and is situated on the right immediately as you enter from the first apartment. In the corner of the second chamber between the two passages, and nearly on a level with the ceiling, there is built a recess in the wall answering the purposes of a cupboard, and similar to the "boles" which are placed in the walls of Irish cabins.

The architecture is the same as that of the rest of the building; it extends to the north-east; the entrance is nearly square, but the interior is circular. The floor of the third apartment is 1 foot 8 inches below the end of the entrance passage, of which fact the first of us who crawled in was informed to his cost, as may readily be imagined. The third chamber runs parallel to the second, viz. due north and south, and its form and architecture are similar, except that perhaps the second apartment is more circular.

Vol. 3, pp. 234 — 236 by Samuel C. Hall, Anna Maria Hall


The site is a popular attraction, and is easy to get to: it is signposted from the main Derry - Buncranna road, any you can drive all the way to the summit, where there is a spacious car park. The last time we visited there was a hurling club having a barbecue and playing hurling within the fort, despite the damp weather.

View from the Greenan.
The Greenan of Ailleach. Photograph Robert Welch © National Museums of Northern Ireland.