Workmen plaster stonework as they rappel down a vault at the reconstruction site during French President Emmanuel Macron's visit at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS TPX IMAGES OF THE DAY 

Workers at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool TPX IMAGES OF THE DAY 

Employees measure an oak tree selected to be used to rebuild the spire and the roof of the Notre-Dame de Paris Cathedral destroyed by fire in 2019, in the Berce forest in Jupilles, France, March 8, 2021. REUTERS/Stephane Mahe TPX IMAGES OF THE DAY 

An employee works on an oak tree selected to be used to rebuild the spire and the roof of the Notre-Dame de Paris Cathedral destroyed by fire in 2019, in the Berce forest in Jupilles, France, March 8, 2021. REUTERS/Stephane Mahe 

Scaffolding under a vault is pictured at the reconstruction site during French President Emmanuel Macron's visit at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

A workman stands on scaffolding under a vault at the reconstruction site during French President Emmanuel Macron's visit at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Wooden beams supporting a vault are pictured at the reconstruction site during French President Emmanuel Macron's visit at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Construction plans are laid out under a vault at the reconstruction site during French President Emmanuel Macron's visit at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

A workman stands on scaffolding under the vault at the reconstruction site during French President Emmanuel Macron's visit at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

A bird statue is seen at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, with buildings and rooftops in the background in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

French President Emmanuel Macron speaks with a worker and the French Army General Jean-Louis Georgelin in front of a stained glass window under the damaged vaults during a visit at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Workers look at the vaults at the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

A scaffolder works under the vaults at the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

A worker looks at the roof of the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Busy workers stand near a stained glass window under the vaults at the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Workers stand on a scaffolding under the vaults at the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

A general view of the main scaffolding under the vaults at the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Busy workers are seen near a stained glass window under the vaults at the reconstruction site during a visit of the French President at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

French President Emmanuel Macron, Paris Mayor Anne Hidalgo and French Army General Jean-Louis Georgelin, in charge of Notre-Dame Cathedral reconstruction, visit the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

French President Emmanuel Macron, Paris Mayor Anne Hidalgo and French Army General Jean-Louis Georgelin, in charge of Notre-Dame Cathedral reconstruction, visit the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. Ian Langsdon/Pool via REUTERS 

Workers at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

Scaffolding at the reconstruction site at the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

A crane and scaffolding at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

View of the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

Bags of lead are seen at the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

A worker at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

Workers at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

A view shows the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

Workers at the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

Workers at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

View of the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

Workers at the reconstruction site of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

View of the reconstruction site of the roof of the Notre-Dame de Paris Cathedral, which was damaged in a devastating fire two years ago, as restoration works continue, in Paris, France, April 15, 2021. REUTERS/Benoit Tessier/Pool 

An employee prepares to fell an oak tree selected to be used to rebuild the spire and the roof of the Notre-Dame de Paris Cathedral destroyed by fire in 2019, in the Berce forest in Jupilles, France, March 8, 2021. REUTERS/Stephane Mahe