It is sobering to realize that James Levine is opening his 16th season as Ravinia’s music director this week, for it seems like only yesterday that this unknown, bushy-haired wunderkind from Cleveland was jumping in at a few days notice for an indisposed Istvan Kertesz. The rest, as they say, is history, and we have since learned to share Levine with New York’s Metropolitan Opera (where he has been music director since 1976) and the major podiums and opera houses of the world. With the games of musical chairs presently being played in the music world, it seems inevitable that his glory days at Ravinia will soon be coming to an end (he is the most obvious candidate to replace Herbert von Karajan in Berlin), but it’s not too late to hear Levine and the CSO at the peak of their unique partnership. Opening night brings the Verdi Requiem, a powerful work that will spotlight Levine’s masterful blending of voices and orchestra. With Levine’s Met connections, his Ravinia programs usually bring the world’s top singers, and the Requiem is no exception; opera superstars Tatiana Troyanos and Samuel Ramey will join Andrea Gruber and Neil Shicoff, along with the stellar Chicago Symphony Chorus. His Saturday and Sunday programs spotlight Bartok’s greatest symphonic works, the Concerto for Orchestra and the haunting Music for Strings, Percussion and Celesta respectively, in programs that will also include Gustav Holst’s colorful masterpiece The Planets on Saturday, and the Brahms First Piano Concerto (with soloist Stephen Hough) and Stravinsky’s Symphonies of Wind Instruments on Sunday. Tonight and Saturday, 8:30 PM, and Sunday, 7:30 PM, pavilion, Ravinia Festival, Green Bay and Lake Cook Rds., Highland Park; 728-4642.