Toponymists have argued about the name Tintagel for nearly nine centuries. The probability is that it is Norman French. The earliest reference, Geoffrey's Tintagol, would have been pronounced with a hard g, like English girl. By the time Layamon wrote his Brut in early Middle English, around 1200, the spelling Tintaieol implies a soft j-like sound, closer to the French ageul. An alternative Celtic etymology proposed by Oliver Padel reads the name as Cornish din-tagell, meaning fort of the constriction - a fort on a narrow place - and the narrow neck of land joining Tintagel Island to the mainland fits the description exactly. The village itself was always known as Trevena, village on a mountain, until the Post Office adopted Tintagel in the mid-nineteenth century. Tintagel had been just the headland and the parish; the Post Office, in the way of post offices, made it the village too.

In Geoffrey of Monmouth's Historia Regum Britanniae, written around 1136 and almost instantly a bestseller across Norman Europe, Gorlois, Duke of Cornwall, hides his wife Igraine at the oppidum of Tintagol on the shore of the sea while he goes off to war. Merlin disguises Uther Pendragon as Gorlois, and Uther enters Tintagel, sleeps with Igraine, and fathers the child who will become King Arthur. The motif - the disguised conception, the predestined hero - was already old when Geoffrey wrote, but his version stuck. Every medieval chronicler and chivalric romance that followed accepted Tintagel as Arthur's birthplace. The castle whose ruins now crown the headland was built in the 1230s by Richard, Earl of Cornwall, the brother of King Henry III, who chose this exact spot precisely because Geoffrey had made it famous. Tintagel Castle is, in a sense, a real building constructed inside a fictional story.

The archaeology tells a different and arguably better story. C. A. Ralegh Radford's excavations in the 1930s, and later digs through the late twentieth century, revealed that Tintagel headland had been a high-status occupation site in the fifth and sixth centuries - the period immediately after the Roman withdrawal from Britain. Either a Celtic monastery, in Ralegh Radford's original interpretation, or - more likely, according to later excavators - a princely fortress and trading settlement. The pottery proved it. Sherds of Mediterranean amphorae that had carried wine and oil, fine red African slip-ware tablewares, glass: trade goods from across the Roman world arriving in post-Roman Britain at a scale that no one had previously imagined possible. Sub-Roman Britain was not the isolated outpost the textbooks had claimed. Someone in Cornwall in the year 500 was drinking wine from Anatolia. In 1998 excavators found a slate inscribed with sixth-century Latin names including Artognou - which has fed more romantic Arthurian speculation, though historians do not believe the inscription refers to King Arthur.

Bossiney and Trevena were established as a borough in 1253 by Richard, 1st Earl of Cornwall, the same Richard who built the castle. The borough sent two MPs to the House of Commons from about 1552 until 1832; the members included Sir Francis Walsingham, Sir Francis Drake, and Francis Bacon - politicians who almost certainly never visited the place they nominally represented. "Tintagel declined towards the end of the medieval period for it was ill-equipped to take up fishing as an alternative occupation," wrote the geographer W. G. V. Balchin in 1954, "paradoxically it now enjoys a temporary prosperity as a result of tourist interest in the castle which was converted so romantically by Geoffrey of Monmouth into an ancient residence of King Arthur." That "temporary prosperity" has now lasted two centuries. The Tintagel Old Post Office, a fourteenth-century yeoman's house, is now a National Trust Grade I listed building. The Camelot Castle Hotel, built in 1899, sits in pseudo-medieval grandeur on the cliff above the harbour. King Arthur's Great Halls, built in the early 1930s for the custard powder magnate F. T. Glasscock to house his Fellowship of the Knights of the Round Table, holds seventy-three stained-glass windows by Veronica Whall depicting the Arthurian tales. Many of the visitors do not want to know about the trading post.

The cliffs around Tintagel are made of old Devonian slate, which contains traces of copper. In strong sunlight, the seawater shows a turquoise green that is genuinely strange - a colour you can read as enchanted or as a function of mineralogy, your choice. The Tintagel Slate Quarries, worked from the fifteenth century until the early twentieth, are largely responsible for the jagged coastline south toward Trebarwith Strand. Composers have come: Arnold Bax wrote his symphonic poem Tintagel after a visit; Edward Elgar composed here too. Writers came in droves through the nineteenth century - Tennyson, Dickens, Hardy. Edith Wharton set part of her last unfinished novel The Buccaneers here. The Artognou stone, the Mediterranean pottery, the trading ships from the eastern Empire, the post-Roman princes, the medieval Norman castle built inside a twelfth-century French-language fiction: it is all true, all at once, all on one headland. Geoffrey of Monmouth made up the most famous story ever told about this place. He chose a very good place to make it up.