Experts will spend 700,000 euros ($770,000) to clean up and repair St Peter's Baldachin, which was built in the 17th century by a team led by renowned Baroque sculptor and architect Gian Lorenzo Bernini.

The almost 30-metre-high canopy covers the high altar of the basilica, and was built on the spot where St Peter, the first pope, is believed to have been buried after dying as a Christian martyr under the reign of Roman Emperor Nero (54-68 AD).

"We are facing a giant, and therefore everything we do will be a titanic undertaking," Pietro Zander, head of the art heritage unit of the Fabbrica di San Pietro, the department in charge of the basilica, said about the restoration.

Zander told reporters that the structure is in a "degraded state of conservation", with its gilded decorations obscured by heavy patina caused by dust and particulate matter, and paint peeling off its wooden parts.

Its last major restoration dates back to 1758, he added.

Alberto Capitanucci, another expert at the Fabbrica di San Pietro, said the work will not interfere with religious services, allowing Pope Francis to continue celebrating Mass from the high altar.

He said the restoration - funded by the Knights of Columbus, a Catholic charity - should take about 10 months, so the baldachin will have "a new splendour" when Francis inaugurates the 2025 Holy Year.

The holy year, also known as a Jubilee and held in Rome at least every 25 years, starts on Christmas Eve 2024 with the opening of the Holy Door of the basilica. The event usually attracts millions of pilgrims seeking the remission of their sins.

($1 = 0.9108 euros)

(Reporting by Alvise Armellini, editing by Andrew Heavens)