French President Emmanuel Macron praised on Friday the more than 1,000 craftspeople who helped rebuild Paris' Notre-Dame Cathedral in what he called "the project of the century", five-and-a-half years after fire gutted the Gothic masterpiece.

France on Friday showed off to the world the gleaming restored interior of Notre Dame cathedral, just over a week before the 850-year-old mediaeval edifice reopens following painstaking restoration after the devastating 2019 fire.

French President Emmanuel Macron has told workers who revived Paris' iconic, fire-ravaged Notre Dame cathedral, that they "achieved what was thought impossible."