The catastrophic event that struck London in 1666 was the Great Fire of London. Beginning on September 2 and lasting until September 6, the fire devastated a significant part of the city, destroying over 13,000 homes, numerous businesses, and iconic structures, including St. Paul's Cathedral. The inferno is believed to have started in a bakery on Pudding Lane and rapidly spread due to the wooden construction of buildings and narrow streets. The Great Fire led to fundamental changes in urban planning, fire safety regulations, and the rebuilding efforts that shaped modern London, influencing the architectural landscape of the city for generations.