On April 15, 2019, the roof and spire of the famous Paris monument went up in smoke. It was a disaster, but one that could have been far worse. Using exclusive 3D modeling to reconstruct the fire, Le Monde identified the crucial decision made by firefighters that saved the cathedral.

✅ Subscribe to our YouTube channel now (and ring the bell for notifications 🔔) 👉 http://www.youtube.com/subscription_c...

For more of our coverage on French and international news, culture and opinion, visit our website: https://www.lemonde.fr/en/