The notable historical event that occurred in 1215 at Runnymede was the sealing of the Magna Carta, a charter agreeing to certain legal limitations on the powers of the English king. Signed by King John of England under pressure from rebellious barons, the Magna Carta established fundamental principles such as the rule of law, the rights to a fair trial, and protections against unlawful imprisonment. This document is often considered a cornerstone of modern democracy, influencing various constitutional developments worldwide by emphasizing the idea that the monarchy could not exercise arbitrary power and that subjects have certain inalienable rights.