The great fire that occurred in London occurred in 1666, significantly changing the city's architecture and urban planning. Known as the Great Fire of London, it destroyed a large part of the medieval city, including St. Paul's Cathedral. The disaster prompted a massive reconstruction effort, leading to the establishment of fire regulations and the development of modern building materials and designs. The fire played a pivotal role in transforming London into a more organized and fire-resistant city, shaping its architectural landscape.