Llandeilo is a town in Carmarthenshire, Wales, situated at the crossing of the River Towy by the A483 on a 19th-century stone bridge. Its population is 1,731. It is adjacent to the westernmost point of the Brecon Beacons National Park.
Llandeilo is named after one of the better-known Celtic saints of the 6th century, Saint Teilo. The Welsh word llan signified a monastery or a church. Saint Teilo, who was a contemporary of Saint David the patron Saint of Wales, established a small monastic settlement (clas) on the site of the present-day parish church.
Although there is very little factual detail about the life of Saint Teilo, the way in which he was highly respected in his lifetime, and revered after his death, is shown by the forty-five places dedicated to him, some as far afield as Brittany.
After Saint Teilo's death, two equally important ecclesiastical centres in Wales, namely Llandaff and St David's, laid claim to his body. There is reasonable evidence to suggest, however, that Saint Teilo was buried in Llandeilo, where "he spent a solitary life gloriously". The parish church of Llandeilo Fawr (Great Llandeilo) is dedicated to Saint Teilo, and until 1880 its churchyard encompassed his baptistry.
The early Christian settlement that developed around the Church of Saint Teilo prospered, and by the early 9th century it had attained considerable ecclesiastical status as the seat of a Bishop-Abbot. The Church of St. Teilo soon became a 'mother church' to the surrounding district, acquiring an extensive estate, and possessing one of the principality's most beautiful and finely illustrated manuscripts - the Gospel Book of Saint Teilo. The discovery of fragments of two large Celtic crosses from this period provide further testimony to Llandeilo's importance and indeed prestige as an early ecclesiastical centre.
Towards the end of the ninth century, the importance of Llandeilo as a spiritual centre had started to decline and the Gospel Book of St. Teilo was removed to Lichfield where it became commonly known as the Lichfield Gospels or the Book of Saint Chad. The Bishops of Lichfield still use this manuscript to swear allegiance to the Crown.
Dinefwr Castle (anglicized as Dynevor) is a spectacular Welsh castle overlooking the River Tywi near the town. It lies on a ridge on the northern bank of the Tywi, with a steep drop of several hundred feet to the river. Dinefwr was the chief seat of the kingdom of Deheubarth and the seat of Rhys ap Gruffydd, one of the early kings of Wales. The foundations of two Roman forts have been discovered in the grounds of the Dinefwr estate, which is in the custody of the National Trust. The estate of Golden Grove lies near the town, and further away, the impressive Carreg Cennen castle, another Welsh stronghold. The remains of Talley Abbey can be seen six miles away to the north of the town. Ten miles further north are the remains of the Roman gold mines of Dolaucothi, another National Trust property.