The Notre Dame fire of 2019 may have caused significant damage, but it also presented archaeologists with an opportunity to delve deep into the cathedral's history. Now, information is coming to light about the cathedral's innovative architecture, which was hidden for centuries.
One of the biggest surprises that the archaeologists found was a thousand iron staples that had been used by medieval builders of Notre Dame to bind its stones together. These staplers have been found in various places around the cathedral, some dating back to the 1160s. Until now, modern experts believed that the Gothic builders of the cathedral only employed iron armatures in restoration work during the 19th century. However, the use of iron turns out to be much more common than originally thought, dating back to the cathedral's construction. "Notre Dame is now unquestionably the first known Gothic cathedral where iron was massively used to bind stones as a proper construction material," say the archaeologists.
This innovative reinforcement was used to bind the outer ambulatory's cross-ribs, which peaked at almost 11 meters high and had to be maintained without any internal support. The first master builder of Notre Dame made a wise choice by using iron, a more durable material that could be more easily concealed, instead of wooden tie rods stretched between the arches. Metal detectors used by the archaeologists have revealed hundreds of metal staples used in the cathedral's nave. While these staples could not be accurately dated, they look different from the staples on the floor. Experts believe that they were the work of a later architect between 1170 and 1190 CE. This architect may well have adopted the staple technique from the original masonry master and taught it to the next in charge of the cathedral. A row of staples at the top of the building suggests that structures were erected after the framework was laid down, demonstrating that the technique was used for a long time period.
The use of iron in Gothic architecture has generally been assumed to be restricted to modern upgrades. However, the research shows that the technique predates restoration work by at least six centuries. This has implications for how we understand Gothic structures and paves the way for more research to uncover further hidden secrets of iconic historical buildings.