The original Deudraeth Castle was built by Gruffydd ap Cynan beginning about 1175, making it one of the earliest Welsh castles to be built in stone (although possibly a drystone construction rather than masonry). That castle is mentioned by Geraldus de Cambrensis in his "Journeys through Wales". Little of that earlier castle remained in the mid C19 when the property was aquired by David Williams. Williams, a wealthy attorney, built a fanciful villa in mock-Gothic style on a high promontory overlooking Portmeiron village.
The scant remains of Castell Aber Ia stand at the south western tip of a short rocky ridge in woodland known as Y Gwyllt to the west of Portmeirion village. All that remains of this small castle is the relatively level rock platform some 20m east-west by 26m north-south, upon which a stone tower once stood. The south, east and western sides of the platform are defined by steep crags some 6-7m high, whilst to the north, the platform has been cut off from the gently sloping ridge by a rock cut ditch and counterscarp bank. Across this side of the platform, small sections of dry stone walling suggests there was once a curtain wall here, and it seems likely this would also have been where the gate was located, accessed by a bridge across the ditch. Two other small sections of surviving wall suggest that other defensively weak points around the circuit may also have been strengthened. The castle was demolished in the mid-nineteenth century by a tenant of the Aber Ia estate. Prior to this it served as a scenic viewpoint with the tower described in the nineteenth century as being semi-circular in shape and some 4m in diameter. The Campanile in Portmeirion village bears a plaque noting its construction from the stone of the castle; whilst the original site is now known as `Castle Rock¿ and used as a viewing point. Here sections of battlemented wall were constructed at the tip of the ridge by Clough Williams-Ellis in the 1960s, and a circular gazebo placed on the eastern edge of the platform in 1983. This castle has often been associated with the `Castle of Deudraeth' mentioned by Gerald of Wales as newly built in 1188; there is however some debate over this association. It does however seem likely that Aber Ia was one of a small cluster of early stone-built castles constructed in Gwynedd at the end of the twelfth century, together with Carn Fadryn (NPRN 95275), Dinas Emrys (NPRN 95284), Tomen Castell (303046) and Castell Pen-y-garn (NPRN 407747). These were not placed to withstand alien invasion, but rather as an expression of a Prince's power and lordship in the unsettled period following the death of Owain Gwynedd in 1170 and the subsequent division of the Kingdom between his sons. (CofleinLouise Barker, RCAHMW, 5th June 2008-06-05)
Gareth Hughes, the Conservation Officer for Broadland District Council writes that:-
"The existence of Castell Deudraeth, mentioned by Gerald of Wales in 1188 as a stone castle, "lately erected" , is not in doubt, but the connection of the structure seen in the twelfth century to the putative archaeological site currently identified with it is not yet proven. The 1983 Centenary Gazebo high above the Town Hall stands on an isolated, flat-topped outcrop of rock (the topography is blurred by planting established over the last 170 years and the site needs close inspection and the minds eye to envisage it without the close tree cover). This outcrop is part of a ridge which extends away to the north east, but this south western end of the ridge it has been severed from the rest of the rock by a narrow, mostly man-made, cutting. On the southern (ie north-facing) side of this cutting a short section of dry-stone walling still survives, partly concealed by modern shrubs, which is clearly the feature interpreted as the abutment of a bridge, spanning the cutting, in the Gwynedd Sites and Monuments Record, based on a series of surveys and other investigations in the early twentieth century. With the exception of this section of wall, the other apparent ruins on top of the outcrop are of two main phases, the initial short section of wall having been built by Clough Williams-Ellis (presumably with the intention of eventually enlarging it into something more impressively castle-like) and the longer, straggling sections (with the start of a couple of arrow-slit windows) dating only from the mid 1980s (the present writer saw them under construction in 1987). Although a motte is usually entirely man-made, in this case, as at several other Welsh royal castles such as Dolwyddelan nearby, a naturally defensible site has been made more secure by modification. Though the lack of a continuous documentary record makes it impossible to be certain, if Gerald of Wales Deudraeth existed anywhere on the Portmeirion peninsula, the only site which presents itself as likely is this one. A rather poorly-researched website on Portmeirions history http://www.portmeirion-history.co.uk/
has, through a lack of care in comparing maps and a lack of understanding of the archaeology, dismissed this site out of hand but conjured up several other potential, phantom, sites for the castle."
Paul Martin Remfry produces evidence to suggest this site is not Gerald's stone castle of Deudrath and, indeed, not the site of a medieval castle of any form at all. Topographical it might be the site of a fortification (of pre-historic or medieval date) but Wales abounds with such potential sites. Remfry identifies Deudraeth with Criccieth Cadtle
although an alternative may be a precursor welsh castle on the site occupied by the Edwardian Harlech Castle