The Cradle of Liberty seems just the city for Gioachino Rossini’s operatic paean to Liberty par excellence. Yet according to the Boston Lyric Opera, their season-opening William Tell is Beantown’s first in better than a century and a half. Written for the Paris Opéra at the pinnacle of its prestige, William Tell marked the 37-year-old composer’s farewell from the stage, with more than half his life still before him. Of all his operas, it is by a wide margin and against steep competition the grandest and most symphonic. From its four-movement overture (”Hi-yo, Silver!”) to the grandiloquent mountaintop choral scene for Switzerland’s founding fathers, not to forget the hero’s time-stopping plea with his son not to move a muscle when Dad levels his crossbow at the apple on the boy’s head, this is music of thrilling color and imagination. And we haven’t even touched on the love story, with its retro bel canto fireworks! Vita Tzykun and David Adam Moore, who share directing and design credits, bring to the party experience in vocal performance, television specials for the likes of Lady Gaga, gallery art, and eye-popping costume couture. The Boston Lyric’s veteran music director David Angus, in demand at leading institutions around the globe, is the conductor. The Metropolitan Opera stalwart George Gagnidze takes the noble title role, facing down James Demler as Gessler, Switzerland’s Austrian oppressor. Anya Matanović and Konu Kim appear as Mathilde and Arnold, lovers in defiance of their hereditary political allegiances. —Matthew Gurewitsch