25, is an opera in a prologue, two tableaux and an epilogue by Sergei Rachmaninoff to a Russian libretto by Modest Ilyich Tchaikovsky.

It is based on the story of Francesca da Rimini in the fifth canto of Dante's epic poem The Inferno (the first part of the Divine Comedy).

11 January) 1906 at the Bolshoi Theatre, Moscow, with the composer himself conducting, in a double-bill performance with another Rachmaninoff opera written contemporaneously, The Miserly Knight.

[1] The setting is the Malatesta castle around the end of the 13th century The ghost of Virgil leads the poet Dante to the edge of the first circle of the Inferno.

Virgil tells Dante that this is the realms where sinners given over to lust are punished, buffeted by an eternal whirlwind.