The historic document signed in 1215 is the Magna Carta, also known as the Great Charter. It was signed at Runnymede, near Windsor, by King John of England after persistent demands from a group of rebellious barons. The Magna Carta is significant as it established the principle that everyone, including the king, is subject to the law, laying the groundwork for constitutional governance. Although it initially focused on specific grievances of the nobility, it has come to symbolize broader human rights and liberties, influencing many democratic constitutions around the world and the evolution of legal systems.