The Great Chicago Fire occurred in the year 1871, specifically from October 8 to October 10. This devastating fire started in a barn owned by the O'Leary family and quickly spread, fueled by wooden buildings and dry conditions. The blaze resulted in the destruction of approximately three square miles of the city, leaving over 100,000 residents homeless and claiming around 300 lives. The Great Chicago Fire profoundly impacted urban development, leading to changes in building codes and fire safety regulations. It also catalyzed the rebuilding of Chicago with more fire-resistant materials and the establishment of the modern city as a major economic hub.