The Grianán of Aileach ( ; ), sometimes anglicised as Greenan Ely or, locally, as Greenan Fort, is a hillfort atop the high Greenan Mountain at Burt on the Inishowen Peninsula in County Donegal, Ireland. The main structure is a 19th-century reconstruction of a stone ringfort, thought to have been built by the Northern Uí Néill, in the sixth or seventh century CE;Bartlett, Thomas. A Military History of Ireland. p.37 although there is evidence that the site had been in use before the fort was built. It has been identified as the seat of the Kingdom of Ailech and one of the royal sites of Gaelic Ireland. The wall is about thick and high. Inside it has three terraces, which are linked by steps, and two long passages within it. Originally, there would have been buildings inside the ringfort. Just outside it are the remains of a well and a tumulus.
By the 12th century, the Kingdom of Ailech had become embattled and lost a fair amount of territory to the invading Normans. According to Irish literature, the ringfort was mostly destroyed by Muirchertach Ua Briain, King of Munster, in 1101.
According to Tony Nugent, the Grianan was also used as a Mass rock during the anti-Catholic religious persecution that began under Henry VIII and ended only with Catholic Emancipation in 1829.
Substantial restoration work was carried out in 1870. Today, the site is protected as a national monument and is a tourist attraction.
Description and interpretation
The Grianán is located on the western edge of a small group of hills that lie between the upper reaches of Lough Swilly and Lough Foyle. Although the hill is comparatively not that high, the summit dominates the neighbouring counties of Londonderry, Donegal and Tyrone. Located at the edge of the Inishowen peninsula, it is northwest of the ecclesiastical site of Derry. The histories of the sites are closely linked. There is much legend and historical material related to the Grianán of Aileach. The Irish annals record its destruction in 1101. The main monument on the hill is a stone cashel, restored in the 19th century, but probably built in the eighth century CE. The summit's use as an area of settlement may go back much further. A tumulus at the Grianán may date back to the Neolithic age. A covered well was found near the cashel in the early 19th century.
Irish antiquarian George Petrie first surveyed the Grianán of Aileach in the 1830s. At this time the cashel was nothing more than a mere ruin. He gives a description of the hill and the monument. The eastern ascent of the hill is described as gradual but within of the top, it terminated in a circular apex. An ancient road between two ledges of natural rock led to the summit. The cashel was surrounded by three concentric ramparts. Petrie suggests that, in the fashion of other monuments of this type such as Emania, the whole hill may have been enclosed by many other ramparts. There is no physical or historical evidence for this. The ramparts that remained were made of earth and stone and follow the natural form of the hill with an irregular circular pattern. They ascend above each other creating levelled terraces. The circular apex of the hill within the outermost enclosure contains about , within the second about and within the third about . Currently, the innermost bank is very low, worn and heather-covered but traceable for almost its entire circuit. The other two banks are in a similar state but are untraceable for long sections. Between the inner most rampart and the cashel, the road dwindles in its width and curves slightly to the right. This "path" was strengthened on either side by walls. At the time of the survey only the foundation stones of these walls remained. Petrie's plan of the site shows a line of stones leading up to the entrance. These are now gone.
The ruins of the cashel itself are described as being a circular wall enclosing an area of in diameter. The wall had a height of with a breadth varying from to . While not perpendicular, it had an inclination inwards indicating its similarity to most other Irish stone forts. Petrie suggests that it was probably originally between twice and four times as high as it was when he surveyed it. up on the interior side of the wall, the thickness was due to the presence of terracing. The terrace is reached by flights of steps on either side of the entrance gateway. Fallen stones had covered any other existing stairs. Petrie suggests that there were originally three or four such terraces ascending to the top of the wall. On each side of the entranceway, there are "galleries" within the wall. Their precise purpose is not clear and they do not connect with the entrance. These two wall-passages, one on the south and another from the northeast run towards the gateway, but stop short. Near the north end of the south passage is a small recess in its west wall. At the south end of the north passage there is a seat-stone.
The current hillfort, after the restoration of 1874–1878, is substantially different but much of the old structure remains intact. During the restoration, it was found that parts of the original drystone masonry had been preserved under the collapse. The workers marked, in tar, the undisturbed portions of the cashel and used the collapsed stone to build on this foundation. They supplemented these with other stones from the area to replace those 'removed by King Murdoch O'Brien in 1101'. The internal diameters of the cashel are 23.6 metres north to south and east to west. The lintel-covered entrance is long, wide and metres high. Before the restoration, the gateway's lintel was not in place. It was wide and high. It leads into the fort from the east. Slight recesses on either side of the entrance way have been filled in. They were probably to allow double leaves of an original doorway to fold flush against the wall. The interior rises in three terraces accessible by stairways which are previously mentioned. The outer wall is a dry-stone construction.
On each side of the entranceway, there are "galleries" within the wall. Their precise purpose is not clear and they do not connect with the entrance. These two wall-passages, one on the south and another from the northeast run towards the gateway, but stop short. The south wall passage entrance is wide, high and long. It turns through a right angle where it becomes wide, high and long. Near the north end there is a recess on the west side wide, and deep. The northeast gallery entrance is wide, high and long. It meets the main part of the passage in a T-junction. To the north, the passage is wide, high and long. To the south, the passage is wide, high and long. Near the north of end of the south passage is a small recess in its west wall. At the south end of the north passage there is a seat-stone. The interior of the cashel is fairly level but Petrie recorded the remains of a small oblong church measuring by . The walls were thick and not more than high. The structure was constructed of mortar but nothing remains of it today. A drain runs through the cashel wall at ground level on the northwest side. It leads from a midden in the western side of the enclosure that was in diameter and one foot deep.
There are many clues that the Grianán of Aileach is a multi-period site. Brian Lacy suggests that the earthen banks surrounding the fort probably represent the defences of a hillfort of the late Bronze Age or Iron Age. Between the two outer banks on the south side of the hill, is the formerly covered spring well which is dedicated to St Patrick. Petrie describes the tumulus, between the second and third wall, as being a small mound surrounded by a circle of ten stones. These stones were laid horizontally and converged towards the centre. In Petrie's time, the mound had been excavated but nothing to explain its meaning was discovered. It was subsequently destroyed but its former position is marked by a heap of broken stones.
During the excavation work of the 1870s, Bernard documented the discovery of many artefacts. Behind a niche in the doorway, a large stone wide was found. It had a round hole in the centre, deep and in diameter. A rotten piece of wood was found in the hole. Bernard was unable to decipher its use suggesting only that it could have been a sundial.
Bernard discovered many animal bones including sheep, cattle, goats and birds. He found stone items including "sling-stones", "warrior's clubs" and a "sugar-loaf-shaped stone with a well-cut base" long, round base, round centre and round top.
The most interesting stone object was "a slab of sandstone, chequered into thirty-six squares", which Lacy believed to be some kind of gaming board. Among the miscellaneous items found were a plough socket, an iron ring, some coins and a bead.
Reconstruction Between 1835 and 1874, the hillfort was going through a state of reconstruction under Walter Bernard of Derry. Bernard, before construction, only had evidence of the base layer of the monument, with other pieces still present being described as a 'mere ruin.' The height from the best surviving walls were given as approximately 6 ft, whilst having an obvious batter, and sloping inwards like Staigue Fort in County Kerry. From this, Bernard concluded that he would look to another monument for reference on design and scale: Staigue Fort in County Kerry in the south-west of Ireland is where he deduced the architecture for the monument. This led him to reconstruct the cashel based on the architecture found in County Kerry rather than the county that the original site was in, which was County Donegal in Ulster. The reconstruction by Bernard has impacted the site as it is a reconstruction done in a more modern time. The reconstruction resulted in poor and crude engineering, with the site left crumbling after being taken over by state care 30 years after the reconstruction. After a later investigation was completed, it was noted that during the reconstruction, Bernard did not have enough of the good-quality stone that he was using on site. The only way for the state to improve the structure is if they improve what Bernard had already built on top of it. This means that the architecture and what we see comes from a second-hand account of what Bernard thought Grianan of Aileach would have looked like from his deductions whilst looking at the Staigue Fort in Kerry.
Morphology
The Grianán of Aileach, at its broadest description, is a ringfort. More precisely it is a multivallate cashel hillfort.
A ring fort can be described as a space, usually circular, surrounded by a bank and ditch or simply a rampart of stone. The bank is generally built by piling up inside the fosse the material obtained digging the latter. Ringforts vary considerably in size and style. In more elaborately defended examples, such as Aileach, the defences take up a much greater area than the enclosure itself.
Matthew Stout gives many examples of why the people who built these structures chose a circular formation. First of all, they had strategic advantages. Circular sites allowed for a broad perspective of the surrounding area and allowed the maximum area to be enclosed relative to the bank constructed. He also comes up with some much more metaphysical theories. He suggests that a circular formation linked the site and its occupants with the circular burial mounds of their ancestors. About a third of all Irish hillforts have mounds or cairns within them. The Aileach is no exception. He also puts forward the idea that a circular form was favoured because corners could act as a dwelling-place of evil spirits. He bases these claims on ethnographic comparisons.