Richard Wagner’s Parsifal, his final opera, was created in parallel with his greatest creations including The Ring and Tristan. Beginning in the 1850’s, its prose and poetry was returned to over and over again in first and second drafts, and was finally orchestrated and presented in 1882; it occupied over a quarter century in Wagner’s creative life. The work was scored with the acoustics of the newly built Bayreuth in mind and has one of the oddest operatic history’s imaginable.
There are essentially two versions of Don Carlo for Giuseppe Verdi. I don't mean that one is in French and the other Italian. Historians and musicologist are manic about the fact that this is untrue; however, there is a work, Don Carlos (francophone's are insistent on this), originally written in French for the Paris Opera that was so vast (5 hrs and change, they say), and it's richness so prodigal, that it obscured the works greatness.