Restoration work on the Notre Dame Cathedral is at a standstill during the containment period caused by COVID-19 outbreak, in Paris, France, April 15, 2020. (Photo by Aurelien Morissard/Xinhua)

Restoration work on the Notre Dame Cathedral is at a standstill during the containment period caused by COVID-19 outbreak, in Paris, France, April 15, 2020. (Photo by Aurelien Morissard/Xinhua)

Restoration work on the Notre Dame Cathedral is at a standstill during the containment period caused by COVID-19 outbreak, in Paris, France, April 15, 2020. (Photo by Aurelien Morissard/Xinhua)

Restoration work on the Notre Dame Cathedral is at a standstill during the containment period caused by COVID-19 outbreak, in Paris, France, April 15, 2020. (Photo by Aurelien Morissard/Xinhua)