The 2019 fire in Paris’ Notre-Dame Cathedral destroyed the Gothic structure’s wooden roof and toppled its iconic spire. But the disaster comes with a small silver lining: Due to the fire—and the ongoing restoration process—researchers are getting an unprecedented look at the cathedral’s inner workings.
According to a paper published in the journal PLOS One this week, large iron staples have been found holding together the cathedral’s stone blocks. In light of this unexpected discovery, scientists say that Notre-Dame is the first known Gothic cathedral to make such extensive use of iron as a construction material.
Crews began work on the cathedral in 1163 and finished in 1345. Researchers now know that they used hefty iron staples—measuring nearly 20 inches long and weighing between 3 and 9 pounds—to reinforce the stone blocks that make up the cathedral’s walls, nave aisles and tribunes. Prior to the fire, the staples supported load-bearing areas of the cathedral, “indicating the iron crucially improved the cathedral’s structural integrity,” as Gizmodo’s Isaac Schultz writes.
