Not an opera but an excellent and probably unique movie: Umbrellas of Cherbourg

One of the gags in Jacques Demy's 1973 The Umbrellas of Cherbourg is at the outset when the male lead, a young French auto mechanic (in itself a bit of a joke) says he's taking his "girl" to the opera (Carmen) and one of the other mechanics opines that he hates operas, he prefers movies. Of course Umbrellas has operatic aspirations - as most know, the entire movie is sung, with not a line of spoken dialog. To be clear - Umbrellas is by no means an opera; musically and lyrically its not even close to the complexity, variety, or vocal challenges of even the simplest of operas. Umbrellas is truly sui generis, and as long as you keep your expectations, musically at least, at the right level, it's a charming, original, and visually extraordinary film. The scene compositions are entirely striking -0 from the opening shots of the working harbor, the cobblestone streets glistening in rain, the many storefronts on the crowded streets gleaming under streetlights, and most of all the nearly surreal, expressionistic interiors with wallpaper in bright hues and with the characters adorned in matching colors and patterns - quote incredible. The story itself is sweet and (spoilers here) most viewers expect the story to be a sentimental romance, but there are very dark and surprising turns toward the end - though the movie ends with the joyous image of the make lead, Guy, playing with wife and daughter in the snow in front of his gleaming Esso service station - like one of the toy models in his that we see in his childhood bedroom now come to life - yet there's a strong undertone of sorrow, loss, and betrayal - and of course a very French frankness about sex, unusual even for French films in its day. Our course Catherine Deneuve is another reason to watch the film - she's very young here and hasn't even grown into her full mature beauty, but with her golden hair and graceful step she lights up every scene she's in - especially the Mardi Gras sequence as she works her way across the street, sideways against the flow of the crowd - and at the end we're shocked to see her in the last sequence, older, colder, harder.