This poem has the rhythm of a great ghost story. We don't just mean that it's about spooky stuff. It's also about the way that it sounds, the way it builds from calm and quiet to super dramatic and intense. A good ghost story isn't about the plot; it's all about how you tell it. You have to start off quiet and slow, pulling your audience in.
That's exactly what Poe does here. The opening words ("It was many and many a year ago") are calming, like softly lapping waves. We can't even tell where we are headed. By the middle, he's starting to pick up speed, and the poem starts to drum on your ear like horses' hooves: "That the wind came out of the cloud by night, / chilling and killing my Annabel Lee." If he was telling it as a ghost story, he would be leaning in now, his face getting closer to the firelight, and his voice would get louder and more intense. Then, at the end, the poem explodes and gives you the big payoff you've been waiting for. The words go off like gunshots: "my darling, my darling, my life and my bride." That's the moment in the ghost story when the person telling it suddenly shouts, and everyone jumps ten feet in the air. The whole rhythm and sound of the poem is designed to build up to that final, terrible scream of passion and frustration, and even after we are done it should still be ringing in our ears.