Beethoven’s lone opera, Fidelio, is a dark tale of imprisonment and devotion, but it probably never seemed as starkly brutal as in a production going on this week in Philadelphia. The Philly Fringe festival has taken Fidelio on location, summoning audiences to the long-shuttered Eastern State Penitentiary, long known as one of America’s more brutal prisons. But does realism really improve opera? “The genre, by nature, is grand, while prisons, by definition, are constricted. Not an easy fit… In effect, Eastern State Penitentiary left little room for audience imagination. Like most art, opera is irrational. Explain it too realistically and you’re left not with an experience, but a mere explanation – and maybe good intermission chatter.”