Iron Maiden's upcoming Book of Souls album sprawls out over two discs, with an 18-minute closing track that bassist and band founder Steve Harris is already hailing as a "masterpiece."

Harris took a few minutes out of a recent interview to share his enthusiasm for the song, "Empire of the Clouds," written by singer Bruce Dickinson. "I think it’s a masterpiece, actually," he said. "I think I can say that because I didn’t write it. It sounds like Maiden, but it’s totally different from what we’ve done before."

Recognizing that some fans might balk at a nearly 20-minute song during this short attention-span era, Harris assured readers that "Empire of the Clouds" earns its length. "Eighteen minutes sounds like a long time, but it’s actually such a journey that ... well, it’s best just to leave people to listen to it and see what they think," he hinted. "But it’s very interesting. It’s certainly not boring."

Harris is also looking forward to Maiden's next round of tour dates, scheduled for 2016, which will serve as the band's return to the road following Dickinson's recent cancer scare. "We always feel like every show is sacred these days anyway, and I suppose even more so now after the scare with what’s happened with Bruce," he admitted. "It makes everything more important to us."

With their frontman on the mend and one of the band's most ambitious works waiting in the wings, Harris vowed fans will get their money's worth when they turn out for the upcoming tour. "The Book of Souls is a really powerful album," he insisted. "We’re really proud of it, and we can’t wait to come out and play new songs on tour."

Book of Souls is due in stores Sept. 4, and will be available as a standard release as well as a deluxe edition accompanied by a hardcover book.

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