Aber Garth Celyn was the seat of the Princes of Wales since Aberffraw and Deganwy were destroyed sometime in the early middle ages. With the fall of the Royal House of Wales and the subsequent conquering of Wales by Edward I, the location of Garth Celyn was lost to history. It is only in the last 20 years that we have a better idea of where it might be.
One possibility put forth by CADW, the Welsh Archaeological society, is at ‘y Myd’, which is a man-made mound to the west of the Aber River in the village of Abergwyngregyn. This mound was one of the many motte-and-bailey castles built by Robert of Rhuddlan in his attempts to conquer North Wales in the 11th century (see my video: https://www.youtube.com/watch?v=3zbFDu8bhQg&t=4s )
“Excavations at Abergwyngregyn, near Bangor, unearthed the remains of a medieval hall dating back to the 14th century, the period when Llywelyn the Great and Llywelyn the Last were fighting for Welsh independence.” [a note from Sarah–that the archaeologist would say this is somewhat surprising since Llywelyn was killed in 1282, otherwise known as the 13th century. If the best they can do is the 14th century, then there’s no evidence this hall dates from the time of the princes.]
“A test dig on the same site in 1993, revealed medieval pottery, a bronze brooch and a coin dating back to the post-conquest era.
“You can see a large area with some substantial walls and the floor plan of a medieval hall with large wings either side,” said John Roberts, archaeologist for the Snowdonia National Park Authority.
“There’s also an enclosure which has features that might relate to industrial activity – metalwork or large ovens.”” http://news.bbc.co.uk/local/northwestwales/hi/people_and_places/history/newsid_9140000/9140324.stm
These excavations were covered over in 2010 to protect them.
Another possibility for the location of Garth Celyn, and the one I chose for my books, is just on the other side of the river and includes a still-standing tower, situated on a hill overlooking the Lavan Sands and with a view of Anglesey.
From the Garth Celyn web page (the page is gone, so I just have to quote it here): “During the centuries between 1283 and 1553, the English crown owned the home and allowed it to become derelict, while at the same time expunging any mention of ‘Garth Celyn’ from the written record. It is not until the time of Henry Vlll, that his surveyor, John Leland notes, ‘the palace on the hille still in part stondeth.’
Then, on June 14, 1551, Rhys Thomas of Aberglasney, appointed by Roger Williams, the surveyor of crown lands in north Wales, to be the deputy surveyor, obtained a lease for himself for the house. Subsequently, on 27 April 1553 King Edward VI, seriously ill with tuberculosis, granted the royal manors of Aber and Cemais to William Herbert, earl of Pembroke and William Clerke. Rhys Thomas and his wife, Jane, then built a house among the ruins of the palace.
Culturally speaking, one of the most important records of Garth Celyn is found in the letters written in the last months of Prince Llywelyn ap Gruffydd’s life to Edward I and the Peckham, the Archbishop of Canterbury.
The royal llys of the Welsh princes excavated on Anglesey does not include a motte, and bears no relationship to the kind of Norman construction CADW is proposing the Llywelyns either built or repurposed at Aber. In addition, Welsh rulers were moving from one royal llys to another as administrative centers from before the Normans arrived in Britain. http://www.angleseyheritage.com/key-places/llys-rhosyr/
The Royal Commission of Ancient Monuments has declared it, “the most important site discovered in Wales in this century.”
As the house itself, the following is a written account from 1874:
Aber Village August 1874
The castle of Llywelyn is but a few minutes walk from the centre of the village.
To reach it by the quickest and most picturesque road you have to traverse the nook at the back of the mill and to scramble over the loose stones that rise about the surface of the widespread stream. Once over the somewhat perilous brook, you have to pass a gate, then a field, still following the side of the watercourse. Mounting a steep rustic ascent you find yourself a few minutes more before a huge barbaric Round Tower, the principal and almost only vestige of Llywelyn’s Castle at the present day. Attached to this Tower is an interesting looking structure built entirely we are told of the ruins of the ancient palace. It is at present used as a farmhouse. This most picturesque house is well worth a visit, though from its private isolated character it is known to few out of its immediate neighbourhood.
The farmer’s wife, though little prepared for the intrusion, nevertheless kindly allowed us to traverse the house, contenting herself with showing us alone one particular room in the tower, a clothes press and four chairs, evidently as old as the building itself and quite as primitive.
She also favoured me with a bit of lighted candle and led me to the steps of a vast cellar or dungeon under the tower, telling me to inspect it if I wished, which I hastened to do – I beg pardon, I did not hasten, for the steps down to it were so slimy, damp, and shaky, that any over haste would have been accompanied with serious bodily harm, so needs was to be slow and cautious.
On descending into this cavern, as well as the faint light of the candle would permit of, I noticed several contiguous cells with prison – like apertures. Could these possibly have been dungeons? At least there were good reasons for the conjecture. At the further end of the cavern, or cellar, or prison, or whatever it was and had been, I could perceive the commencement of a subterranean passage, which led, I was afterwards informed, to some solitary spot in the glen – for what purpose, must be left to the imagination, for there are no printed memorials to the spot, nor any written ones, unless Lord Penrhyn, the owner of the property, happens to have any such in the archives of his Castle.