This comprehensive archaeological report has been beautifully produced by its two authors and 28 other contributors from excavations sponsored by the National Museum of Wales and Cardiff University. The site is an early medieval Welsh llys (royal court) situated on a semi-artificial, timber-fortified island in a lake, called a crannog in Irish and Scots Gaelic usage, but a settlement-type otherwise unknown in Wales or England. Its waterlogged remains have preserved many features of its original construction, in addition to evidence for the lifestyle and material culture of its inhabitants, including rare textiles of embroidered silk and linen. Dendrochronology reveals that Llangorse crannog was built during the early 890s in the little kingdom of Brycheiniog, nestled between three mountain ranges and the valleys of the rivers Usk and Wye. It seems to have served as a kind of buffer state between the more powerful Anglo-Saxon kingdoms of Mercia and Wessex to the east, and the larger Welsh kingdoms of Dyfed and Gwynedd to the west and north. Asser, a Welsh bishop from St. David's in Dyfed, notes that the kings of Brycheiniog were in alliance with the West Saxon King Alfred in the last decades of the ninth century, seeking his protection against their Welsh neighbors, especially the kings of Gwynedd, who had allied themselves with the Norse conquerors of Northumbria. During the Viking wars of the late ninth and early tenth centuries, Brycheiniog acquired some further strategic importance, but was forced to play a dangerous game among the shifting alliances of the day. In fact, the new royal refuge was soon overrun by its erstwhile allies scarcely two decades after it had been built, apparently part of "a punitive expedition" (412) against Brycheiniog for an attempt to break free from Anglo-Saxon hegemony. It was directed by Æthelflæd, King Alfred's daughter, who had become "Lady of the Mercians" after her husband Æthelred's death in 911. According to the Anglo-Saxon Chronicle for the year 916, Æthelflæd's forces captured the Welsh king's wife and 33 other hostages at Brecenanmere, Lake of Brecen, the name of the kingdom in Old English or perhaps that of its eponymous founder Brychan. The crannog was then burned to the waterline and permanently abandoned.

Its site was partially excavated in 1867 and duly reported by local antiquaries according to the resources and standards of the day; a new survey and set of excavations were undertaken from 1980 to 2004. Underwater archaeology reveals that the island was built up from the lake bottom with stone, brushwood and tree branches, then fortified with palisades, planks and beams hewn from over 75 large oak trees, including a footbridge on piles to the shore allowing for the passage of pedestrians, handcarts and animals. "The completed oak palisade lines may well have risen over two metres above the summer waterline in order to define the site, protect its occupants and possessions adequately and create at least three distinct contiguous and interlinked enclosures, with extensions" (441). It is unknown whether the interior buildings were round in the traditional manner or rectangular, a newer building design found elsewhere in Wales at the time. Even so, the "Llangorse timber constitutes an unprecedented corpus of structural wood from ninth- and tenth-century Wales, and important evidence for treewrightry and wood-working for western Britain" (146). This evidence reveals continuity with pre-Roman methods, that is, controlled cleaving rather than sawing, as well as cutting and finishing with axes without tight mortise or tenon joints. Eighty-five percent of the timber was oak, with holly for bridge and building posts, and hazel, birch, willow, ash and alder for wall stakes and wattle, revealing extensive royal control of surrounding woodland resources. The Llandaff charters of the early twelfth century reveal the presence of royal properties all around the lake at this time and that the monastery at Llan-gors on the north shore was used to host various royal and ecclesiastical gatherings. Even though Irish influence in the area is only attested much earlier, in the fifth and sixth centuries, the construction style of this island refuge suggests the special recruitment of a skilled project manager from Ireland, one perhaps similar to the imagined speaker in an Old Irish poem, "The Master Builder," who exclaims: "O my Lord, what shall I do with all this great material? When shall these thousand planks be a work of compact beauty?" (148).

Plant remains and pollen evidence reveal the presence of bread wheat, hulled barley, oats, rye and beans, as well as flax for linen and straw or bracken for roof thatch. Pigs account for the bulk of food animals with beef cattle at about 25% and sheep or goats under 20%. Domestic animals were supplemented by choice cuts of red deer and roe deer, a likely product of royal hunting prerogatives. Some of the very large pig bones suggest the occasional wild boar. Most of the bird species are wild, too, mainly duck, but fish bones are rare, with pike predominating at 60%. This absence of fish is surprising, since Gerald of Wales later describes the lake in the late twelfth century as abundant in pike, perch, trout, trench and eels, which is still true today.

Some early medieval metalwork in copper alloy and iron was found at the site, including "objects of faith" like part of a reliquary lid inlaid with glasses characteristic of other portable shrines carried by Irish or Scottish monks in their commotationes (peregrinations) to promulgate the "laws" of particular saints. There are many personal items like bone combs, glass beads, brooches, pins, toiletry articles, drinking-horn terminals, knife blades, etc. Lithic material includes finger rings, quern-stones and whetstones from local sources. The textile remains reveal "exceptional needlework skills combined with a familiarity with exotic silk designs" (312). These probably originated in Anglo-Saxon England, but also anticipate later descriptions in Middle Welsh prose, where the most frequently mentioned elite fabric is pali (brocaded silk). The main decorative scheme is the vine scroll or "tree of life" inhabited by birds and animals, a common feature of Anglo-Saxon art in the eighth century as seen on the Bewcastle and Ruthwell crosses.

Two log boats were discovered at Llangorse crannog, one intact and hollowed out from a single heart-of-oak using about two-thirds of the diameter of the tree with a seat carved for a paddler in the stern; it was still visible on the bottom in the 1860s. The other is a flat-bottomed, plank-built vessel, designed for load-bearing stability with minimal draft.

According to Gerald of Wales, the lake was reported by local residents to display "many miraculous properties," including its appearance sometimes to be "completely covered with buildings or rich pasturelands or adorned with gardens and orchards" (424). Another story was told by Gerald's great-grandfather Gruffudd ap Rhys ap Tewdwr, who died in 1137. While passing the lake with two highborn magnates, Gruffudd was teased by the others about his claim to royal blood and reminded of the legend that the rightful ruler of the land could command the lake birds to sing. They put it to a test, whereupon the first two men tried without result. Then Gruffudd took his turn: "all the birds, each according to his kind, beat the water with their wings and began to sing with one accord and to proclaim him master. Everyone was dumbfounded and astonished" (424). Another legend was that the lake turned green in time of war (perhaps with algae blooms in the late summer fighting season); at other times, it swirled with red eddies as of flowing blood, explained by the volume's authors as the likely run-off from the surrounding plowed fields. When frozen in winter the lake would groan as with the lowing of cattle, a phenomenon which Gerald himself rationalizes as the heaving or cracking of ice. Walter Map, Gerald's contemporary, tells of a faery bride captured from people who lived in the lake when caught dancing by moonlight on the shore, to which she returned with her children when offended by her terrestrial husband. In short, the obviously once-occupied lake served as an imaginative repository for traditional tales about Annwn (The Deep or Otherworld) , as it appears in the later Welsh Four Branches of the Mabinogi, or as an inundated realm similar to the Cantre'r Gwaelod (Lowland Hundred), later said to lie on the bottom of Cardigan Bay with its church-bells faintly audible, or indeed like the mystic lake-isle of Avalon--Ynys Afallon in Welsh--to which the wounded King Arthur is taken by his sister Morgan le Fay after his last battle. Nineteenth-century folklore also tells of church bells heard ringing below the waters of the lake and an Old Woman of Llangorse who "sits on top of the sunken church steeple and pulls down disobedient children into the lake" (434). This body of water even has its own legendary afanc, an aquatic monster similar to Scottish Nessie.

In more recent years, Llangorse Crannog has inspired the production of a community opera, Ynys Gwydr: Island of Glass, which premiered in 2013. The site is currently visible from a viewing platform off the north shore at the Welsh Crannog Centre on Llangorse Lake. The scholarly care and collective effort which has gone into both the excavation of this site and its exposition in this volume is impressive. Together they provide a sharply focused, but penetrating shaft of light into this dark corner of early medieval Wales.