Early Life and Renunciation of the Throne
Cybi was born around 483 in Dumnonia, corresponding to modern Cornwall. His father, Salomon (in Welsh, Selyf), was a warrior prince generally thought to have been a king of Cornwall; his mother was Saint Wenna, also known as Gwen ferch Cynyr, the sister of Saint Non. This kinship made Cybi a nephew of Non and a first cousin of Saint David.
In his youth Cybi received a Christian education and undertook a pilgrimage to Judea and Jerusalem. On returning home he discovered that his father had died and that he had inherited the Cornish throne. He politely declined the throne in favour of religious work, instead travelling through his kingdom preaching and building churches, including foundations at Duloe and Tregony.
Foundations in Wales
Cybi relocated to South Wales, founding a church at Llangybi between Usk and Caerleon in Monmouthshire. He later sailed to north Wales, where he founded another Llangybi on the Llŷn peninsula. Near this church stands Ffynnon Gybi (St Cybi's Well), whose waters have long been believed to hold healing properties.
King Maelgwn Gwynedd granted Cybi the old Roman fort at Holyhead on Holy Island, Anglesey. The site subsequently became known as Caer Gybi ('Cybi's Fort') and the island itself Ynys Gybi ('Cybi's Island'). There, around 540, Cybi established a large and important monastery on the ground where St Cybi's Church now stands, within the surviving walls of the fort. By tradition he is also said to have attended the Synod of Llanddewi Brefi in Ceredigion in 560, a date that sits uneasily with the tradition placing his death in 555.
Caer Gybi and the Roman Fort
The fortlet known as Caer Gybi was a small Roman naval base constructed between the late third and early fourth centuries, serving as an outpost supporting the larger fort at Segontium and defending the western coast against Irish maritime raiders. A watch tower stood on nearby Holyhead Mountain. Both installations were probably abandoned around 393, when troops were diverted to address the revolt associated with Eugenius.
The fortification had three defensive walls with circular watch towers at each corner, the fourth side facing the sea and likely housing a quay for naval patrols; the walls measured about four metres high and 1.5 metres thick with herringbone patterning. When Maelgwn Gwynedd granted the abandoned fort to Cybi in the sixth century, he established his monastery within these walls. The Church of St Cybi still occupies the site, surrounded by the remnants of the Roman walls.
Cybi and Seiriol
Cybi maintained a close friendship with Saint Seiriol. By tradition, Cybi always faced the sun while travelling to meet Seiriol, giving him a tanned complexion and the epithet 'Cybi Felyn' (Cybi the Tanned), while Seiriol, travelling in the opposite direction, remained pale and became known as Seiriol the Fair. Their reputed meeting place at Saints' Ford near Llanerchmedd is commemorated in the name of the Rhyd-y-Saint railway station.
Relics & Shrines
Cybi died on 8 November 555 and was buried in Eglwys y Bedd (the Chapel of the Grave), a chapel adjoining his monastery at Holyhead traditionally marking his burial place. St Cybi's Church, which grew on the monastic site and is now a Grade I listed building, occupies the interior of the Roman fort.
The site suffered repeated depredations. Viking raiders sacked the church in the tenth century, and in 1405 the troops of Henry IV seized Cybi's shrine and relics during campaigns against the rebellion of Owain Glyndŵr, carrying the relics to Christ Church Cathedral in Dublin and effectively ending pilgrimage to the site. During the 1650s, in the English Civil War, Cromwell's forces occupied the church, damaged its fixtures, and raised its tower by some seventeen feet for coastal surveillance.
Veneration
Cybi's feast day is 8 November, with an additional celebration on 13 August in Cornwall. He is venerated in the Roman Catholic Church, the Eastern Orthodox Church, and the Anglican Communion.
