Workers stand next to an excavator robot during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

A worker stands next to a scaffolding during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

The organ is pictured during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

The building's buttress is pictured during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Parts of a destroyed rib vault and scaffolding are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Workers are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Parts of a destroyed ribbed vault and scaffolding are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

General view of damage on the nave and rubble is pictured during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Excavators are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

General view of damage on the nave and rubble is pictured during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

French Culture Minister Franck Riester speaks with French chief architect of historical sites Philippe Villeneuve as they visit the Notre-Dame de Paris Cathedral during preliminary work three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Scaffolding is seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Workers are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

The rosette is seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Workers are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Excavators are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

A part of a destroyed ribbed vault is seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

Parts of a destroyed scaffolding are seen during preliminary work in the Notre-Dame Cathedral, three months after a major fire, in Paris, France July 17, 2019. Stephane de Sakutin/Pool via REUTERS

An aerial view shows the damaged roof of Notre-Dame de Paris during restoration work, three months after a fire that devastated the cathedral in Paris, France, July 14, 2019. REUTERS/Philippe Wojazer

Workers are pictured during preliminary work at the Notre-Dame de Paris Cathedral, in Paris, France July 24, 2019. Rafael Yaghobzadeh/Pool via REUTERS