An 89-year-old film, which could take cinema-goers more than eight hours to watch, is returning to the big screen.
The new digitally restored version of Abel Gance's Napoleon comes at the end of a 50-year project involving the BFI National Archive.
Running at some five and a half hours on screen, the 1927 film demands a huge investment of resources - from projectionists, musicians, conductor and audiences, and in a live performance with intervals the experience adds up to more than eight hours from start to finish.
Cinema screenings where there is no live orchestra are estimated to run to around seven hours, as theatres are likely to have a couple of breaks for the sake of viewers' comfort.
The film features full-scale historical recreations of episodes from the personal and political life of Napoleon, from the French Revolution to the arrival of French troops in Italy marking the beginning of the first Italian campaign of 1796.
Starting later this year, audiences will be able to experience this cinematic masterpiece with Carl Davis's score - the longest ever composed for a silent film - when the film goes on theatrical release in UK cinemas.
The film was first presented, partially restored, at the BFI London Film Festival in 1980.
The latest digital restoration of Napoleon will have its premiere screening with a live performance by the Philharmonia Orchestra of Davis's score in early November at the Royal Festival Hall.
It has been entirely re-graded and received extensive digital clean-up throughout, all of which offers significant improvements in overall picture quality.
It is the most complete version of the film available, compiled by Academy Award-winning film-maker, archivist and historian Kevin Brownlow.
Brownlow spent more than 50 years tracking down surviving prints from archives around the world after he first saw a 9.5mm version as a schoolboy in 1954.
He worked with the BFI National Archive on a series of restorations.
"This is a tremendous step forward for film history," Mr Brownlow said.
Heather Stewart, creative director at the BFI, said: "Several generations of staff at the BFI have worked on this project. Napoleon is a landmark in the history of cinema and we are grateful to all of the great talents who have helped us along the way but especially, of course, Kevin Brownlow for his indefatigable championing of the film and Carl Davis for his amazing score.
"The film will also be available on BFI DVD/Blu-ray and BFI Player.