Workers are seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

The Notre Dame de Paris Cathedral is seen under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

Workers are seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

The Notre Dame de Paris Cathedral is seen under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

Workers are seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

The Notre Dame de Paris Cathedral is seen under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

A worker is seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

Workers are seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

Women wearing face masks walk past the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

A man looks at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

The Notre Dame de Paris Cathedral is seen under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

The Notre Dame de Paris Cathedral is seen under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

Workers are seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

Workers are seen at the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

The Notre Dame de Paris Cathedral is seen under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)

A woman passes by the Notre Dame de Paris Cathedral under repair after it was badly damaged by a huge fire in April last year in Paris, France, July 10, 2020. (Xinhua/Gao Jing)