Giuseppi Verdi's "Don Carlo" was a Behemoth, a lumbering monster. It featured variant openings, duets and trios and choruses to burn, ballet music that now only exists as a separate concert work, and most importantly, a great psychological/musical narrative frame -- the reason for all the elaboration and development.
What most of us know begins in a tomb in Spain and builds out an old and new subtext of European history, the battle of reactionary politics and the spirit of the Reformation. This background weaves this ideological struggle into a love story of great power.