Caernarfon Castle has stood at the mouth of the River Seiont for more than 700 years, and in that time it's hosted a royal birth, survived three separate sieges, and staged two of the 20th century's most televised royal ceremonies. Here's the real timeline behind the stone — not the brochure version.
Before the Castle: Roman Segontium
Long before Edward I arrived, a Roman fort called Segontium stood roughly half a mile from where the castle now sits, garrisoned from around AD 77 until the late 4th century. The Welsh name for the town, Caer yn Arfon ("the fort opposite Anglesey"), likely traces back to this Roman presence — giving the site a defensive history stretching back over a thousand years before construction even began.
1283: Construction Begins
Edward I ordered Caernarfon's construction in 1283, immediately after defeating Llywelyn ap Gruffudd, the last native Prince of Wales, and his brother Dafydd. Edward placed Master James of St George, his most experienced military architect, in charge of the design — alongside new town walls and a quay, built as one connected project rather than separate works. The scale of the undertaking was unusual even by Edward's own standards; he was building not just a fortress but a new seat of royal administration for North Wales, complete with its own walled town.
Caernarfon's design deliberately echoes the Theodosian Walls of Constantinople, with bands of dark and pale stone and polygonal towers — Edward I was making a direct visual claim to imperial Roman authority, not just building a fortress.
25 April 1284: The Birth of Edward II
While the castle was still very much a construction site, Queen Eleanor of Castile gave birth to the future Edward II within its walls. The story that Edward I presented the infant to Welsh nobles as "a prince born in Wales who spoke not a word of English" is a later legend rather than contemporary fact, but the birth itself is well documented — and it set up the tradition, still followed today, of the English monarch's eldest son holding the title Prince of Wales.
1294–95: Madog ap Llywelyn's Revolt
Welsh resistance to Edward's conquest didn't end with Llywelyn's death. In 1294, Madog ap Llywelyn led a major uprising across North Wales. Caernarfon, still unfinished and only lightly defended, was overrun and partly burned. Edward I responded by recapturing the town and ordering the castle's defenses substantially strengthened — work that shaped much of what survives today.
1301: The First English Prince of Wales
In 1301, Edward I formally created his son — the same Edward born at Caernarfon in 1284 — Prince of Wales, establishing a title that English and British monarchs' heirs have held ever since. This is a separate event from a formal investiture ceremony at the castle, which didn't happen until centuries later.
c.1330: Building Work Winds Down
After roughly 47 years and around £25,000 spent — a vast sum for the period — construction effectively stopped. Large parts of the planned interior, including a grand hall on the upper ward, were never built. Caernarfon was, in a real sense, left permanently unfinished.
| Date | Event |
|---|---|
| AD 77–4th century | Roman fort of Segontium occupies the site |
| 1283 | Edward I orders construction to begin |
| 25 April 1284 | Birth of the future Edward II |
| 1294–95 | Madog ap Llywelyn's revolt; castle and town sacked |
| 1301 | Edward becomes the first English Prince of Wales |
| c.1330 | Building work winds down, interior unfinished |
| 1403–04 | Owain Glyndŵr's forces besiege the castle |
| 1642–46 | Royalist stronghold during the English Civil War |
| 1911 | Investiture of Edward (later Edward VIII) as Prince of Wales |
| 1969 | Investiture of Charles (later Charles III) as Prince of Wales |
| 1986 | UNESCO World Heritage Site inscription |
1403–04: Owain Glyndŵr's Revolt
A century after Madog's uprising, Owain Glyndŵr led a far larger and longer Welsh war of independence. His forces besieged Caernarfon in 1403 and again in 1404, but the castle's English garrison — though small — held out both times. The siege is one of the clearest tests of the defenses Edward I and Master James of St George had designed a century earlier.
1642–46: The English Civil War
Caernarfon was held for the Royalist cause during the Civil War, changing hands more than once before finally surrendering to Parliamentary forces in 1646. This marked the castle's last direct military engagement — after the war, it was left to decay for the best part of two centuries, with stone reportedly removed for other local building projects, and parts of the structure falling into genuine disrepair until restoration efforts began in earnest in the Victorian era.
Don't assume every dramatic-sounding event in Caernarfon's history is verified fact — some popular stories, like the "not a word of English" Edward II legend, are later embellishments rather than contemporary record.
13 July 1911: The First Investiture
After centuries of disuse, the castle was restored in the late 19th and early 20th centuries, setting the stage for its modern role. David Lloyd George, then Constable of Caernarfon Castle and a rising political figure, helped organize the investiture of the future Edward VIII as Prince of Wales in the restored outer bailey — the first formal investiture ceremony ever held at the castle itself.
1 July 1969: The Second Investiture
Fifty-eight years later, the same ceremonial tradition was repeated for the future King Charles III, in a televised event watched by an international audience. The 1969 investiture is the version most visitors today associate with the castle, and several Caernarfon Castle guided tours — including the small-group tour from Holyhead — stop directly at the outer bailey site where it took place.
If the investitures are the part of the history that interests you most, ask your guide specifically to point out the exact spot in the outer bailey — it's easy to walk past without realizing its significance.
1986: UNESCO World Heritage Status
Caernarfon was inscribed as a UNESCO World Heritage Site in 1986, grouped with Edward I's other Welsh castles at Conwy, Beaumaris, and Harlech under the title "Castles and Town Walls of King Edward in Gwynedd." The listing recognizes the group as one of the most complete and ambitious examples of medieval military architecture in Europe.
Where to See This History in Person
Several guided Caernarfon Castle tours weave this timeline into the visit itself, rather than leaving you to piece it together from plaques. For more on the people behind these events — Edward I, Master James of St George, Owain Glyndŵr, and David Lloyd George — see our full history of Caernarfon Castle. For the architectural details that make these events visible in the stone itself, see Caernarfon Castle's architecture and layout.
Visiting Segontium Today
The Roman fort that may have given Caernarfon its name still has visible remains today, managed separately by Cadw and sitting roughly half a mile from the castle — an easy add-on walk if Roman Britain interests you as much as the medieval period. Unlike the castle, Segontium is a more modest, low-walled site, but it's a useful reminder that this stretch of coast was considered strategically important for well over a thousand years before Edward I ever arrived, and that Caernarfon's medieval fortress sits on ground with a much older defensive history.