What was the most expensive silent movie ever made?

"Ben-Hur: A Tale of the Christ", a 1925 American silent epic adventure-drama film, was directed by Fred Niblo and written by June Mathis, based on the 1880 novel "Ben-Hur: A Tale of the Christ" by General Lew Wallace. The film stars Ramon Novarro as the title character and is the first feature-length adaptation of the novel and second overall, following the 1907 short. Regarding the film's production costs, they rose to $3,900,000 ($60,260,000 in 2022) compared to MGM's average for the season of $158,000 ($2,440,000 in 2022), making "Ben-Hur" the most expensive film of the silent film era.

In this version of 'Ben-Hur", a wealthy young Jewish prince is a boyhood friend of the powerful Roman tribune, Messala. When an accident and a false accusation leads to Ben-Hur's arrest, Messala, who has become corrupt and arrogant, makes sure Ben-Hur is separated from his family who are jailed.

Ben-Hur becomes a slave on a Roman war galley. Along the way, he unknowingly encounters Jesus. Once aboard ship, his defiance and strength impresses a Roman admiral, Quintus Arrius, who allows him to remain unchained. This will work in the admiral's favor because when the ship is attacked and sunk by pirates, Ben-Hur saves the admiral.

Arrius treats Ben-Hur as a son, and over the years the young man grows strong. He eventually has a climactic showdown with Messala in a chariot race. Ben-Hur is the victor. Messala doesn't die. Ben-Hur is eventually reunited with his mother and sister.