Notre-Dame Restoration Reveals Advanced Iron Staples in Gothic Construction

The restoration of Notre-Dame Cathedral following the 2019 fire has uncovered iron staples used in its original construction, revealing advanced medieval engineering. The staples, weighing 2-4 kg and measuring 25-50 cm, were found in hundreds on the floor and walls after the fire. Analyzed by Maxime L'Héritier of Université Paris 8 and colleagues, they date to the same period as the masonry and were used in the initial phase to create a load-bearing iron skeleton. This technique allowed the cathedral to achieve unprecedented height, making it the tallest building of its time. The discovery was published in PLOS One. The restoration, costing over €800 million, aims to reopen in time for the 2024 Paris Olympics. Researchers are now testing the staples' strength to reuse undamaged ones, mimicking original methods due to the lack of detailed plans.