King Arthur is one of the most famous and at the same time most mysterious heroes of world history. Everyone knows that he ruled Britain at the turn of antiquity and the Middle Ages, founded the knightly brotherhood of the Round Table, and was associated with the sorcerer Merlin, Avalon and the Holy Grail. However, scientists have long refuted all these claims, calling into question even the very existence of Arthur. There are reasons for this - the sources of the early Middle Ages speak little and indistinctly about him, and the subsequent extensive Arthurian literature is completely fantastic. Nevertheless, in different countries attempts do not stop to find the real Arthur in the pages of history. One of these attempts was made by historian Vadim Erlikhman, who recreated the biography of the legendary monarch based on information scattered across the pages of ancient chronicles, genealogies and novels. A painstaking analysis of facts and versions helps to understand what Arthur was (or could have been) and why the entire European civilization is sometimes called “Arthurian.”