The science that France’s Historical Monuments Research Laboratory (LRMH) has brought to bear on the restoration of Notre-Dame is fascinating. Here’s a snapshot:
To decide which stones can be salvaged, geologists are studying the color of those that have fallen. Heat weakens the limestone used in building the cathedral. Blackened, reddened, or powdery stones will not be reused.
A metallurgist believes that the microscopic structure of the rust from iron bars found near the stones can also provide clues about re-use. These bars may have been used in construction and left in place or added as reinforcement.
An art historian aims to study stones still in place, such as those encasing the rose windows. He also plans to use ground-penetrating radar to get a clearer picture of what lies below the cathedral’s ground floor.
For more detail, check out this article in Science Magazine.
Rebuilding the spire
Shortly after the fire, prime minister Édouard Philippe announced an architectural design competition for a new spire “adapted to the techniques and the challenges of our era.”
Chosen by more than 30,000 members of the public, the design by Zeyu Cai and Sibei Li won out over 226 entries from 56 countries. The proposed spire, called Paris Heartbeat, featured a mirrored surface—and a mirrored roof for the cathedral—that changes moment by moment with the surrounding urban environment plus a time capsule floating at the top.
The status of the restoration
Elegant and innovative as Cai and Li’s spire redesign was, it was ultimately not chosen. In fact, tradition has essentially ruled the day in the restoration of Notre-Dame.
In late November 2020, all damaged scaffolding around Notre-Dame was removed, paving the way to build scaffolding inside the cathedral to protect and support the vaults so they can be rebuilt without risking the integrity of the structure. And in December, the Grand Organ was dismantled and removed so that its pipes could be cleansed of lead dust. Restoration work, reassembly, and turning are projected to be complete by April 2024. From the laying of the first cornerstone—and before—to the completion of repairs and restoration, the story of Notre-Dame is rich with historical and architectural detail. If you’re interested in staying abreast of the restoration, the Friends of Notre-Dame de Paris site makes for fascinating reading.