If you read enough literature ( a crime to which I plead guilty ) you're sure to come across a version of the King Arthur story. The legend has existed for centuries, and has become a steady source of pleasure for those who enjoy historical/fantasy/mystery/military fiction. Scratch the surface of many of these types of stories, and chances are that the King Arthur myth plays a role in inspiring the tale.
There are many who believe that the stories of King Arthur are more than myth or legend. A school of thought teaches that Arthur, or a version of him, was a Celtic warlord who may have lived in the fifth century in eastern Britain, now consisting of Wales or Cornwall. This Arthur is far from the romanticized, chivalric and sanitized version of Chretien de Troyes, Mallory, Tennyson, T.H. White and others: he is more accurately characterized in the novels of Bernard Cornwell and Jack Whyte. While no concrete proof for Arthur's existance has been uncovered, or is ever likely to be uncovered, the very notion of this warrior-statesman-visionary is attractive, especially in the modern world with its dearth of such leadership.
If you believe in the possibility of Arthur, then it follows that there must have been a real "Camelot" or capital where he lived, worked, and tried to fashion a civilized society in the wake of the retreat of the legions of Rome. Again, the romanticized versions of Camelot, complete with Disney-like turrets, banners, damsels in distress, and jousts and jugglers is best left to the cartoons and pot boilers.
The real Camelot must have been a place of comparative civility and amenities, given the time period, but it would have been far from Disneyland. If Arthur existed in the fifth century, he would most likely have used an abandonned Roman garrison town to place his capital. In Britain, there were only three garrison towns large enough to fit his requirements. York, Gloucester, and Caerleon are the three. Only one of them is in Celtic Britain, so the nod goes to Caerleon.
Caerleon today is a peaceful and tranquil town in south-eastern Wales. The Roman ruins that are visible are impressive and evoke a thriving and bustling town that gave comfort and wealth to the Romans stationed in Wales, and, to a large measure, to the local people who lived close by. When the Roman legions were withdrawn in the fifth century, the town would have been almost deserted, dismantled by farmers who needed the stone work for their farms, and fallen into some disrepair. But not to the point of becoming ruins: far from it. If Arthur and his forces chose to locate in Caeleon, they would have been able to repair much of it, using plans and technology only recently left behind by the Romans. Running water, sewers, public baths, and a large amphitheatre could have easily been used by Arthur. The legion's headquarters, now lying under St. Cadoc's Church, could have been Arthur's headquarters and personal barracks: it would have been a large structure, capable of accommodating several officers who would meet to plan training and campaign strategy ( using a round table? ). The Amphitheatre would have been spacious enough for training and for tournaments and competitions, including the timeless competitions in Wales for singing and poetry.
Other towns in Britain claim to be Camelot. They include Winchester, Salisbury, Cadbury Castle ( an iron age hill fort ), and Tintagel in Cornwall. All sites make their claims, but the claims are not plausible: the archeological evidence is either too small or too flawed to sustain the claim. Only Caerleon, situated in Celtic Wales, near a major river, surrounded by productive fields and hemmed in by protective hills and mountains, with a large and established administrative and military town already on site, can sustain a claim. For my money, I believe that I have found Camelot.
Is this important? Probably not, but, in a world increasingly cynical, in societies increasingly bereft of visionary leadership, in a world being swallowed up by the same mindless economic collossus, it would be nice to know, that, for "one brief shining moment", there was a place and a man who could inspire people with the purity and unity of his vision.