The Great Fire of London in 1666 had a significant impact on the city, as it destroyed much of medieval London, reshaping its physical and social landscape. Following the fire, reconstruction efforts led to modern urban planning, with the introduction of building codes to reduce fire risks. Sir Christopher Wren played a crucial role as an architect in redesigning St. Paul's Cathedral and other structures. The Great Fire also shifted public perception, leading to improved sanitation and urban infrastructure. Importantly, it laid the groundwork for the modern London we see today, illustrating how disaster can inspire significant urban reform.