Genesis’ landmark album The Lamb Lies Down on Broadway turns 50 years old this year. Today, they’ve announced they’re marking the occasion with a new Super Deluxe Edition of the double LP, featuring a full remaster, a new Dolby ATMOS mix, a recording of an entire 1975 concert, three previously unheard demos, and various other ephemera from the era.

The Super Deluxe Edition also comes with a 60-page coffee table book with liner notes by Alexis Petridis, who interviewed all five Genesis members. Of the project, Petridis says:

Perhaps it makes sense that an album as complex as The Lamb Lies Down On Broadway has an equally complex history. The saga of its making is a strange and lengthy one, involving rat-infested country houses, uncanny presentiments of the future—or at least the future of rock music—Hollywood directors, personality clashes and inflatable penises. It’s also occasionally controversial: Talking to the former members of Genesis about The Lamb… nearly half a century on, it’s hard not to be struck by the fact that they seldom agree about it. Some members of the band have said they think it’s the best album of their career. Others think of it as a brave but flawed experiment. Some people view it as the absolute apotheosis of early-’70s progressive rock: a double concept album filled with dense, intricate, ever-shifting music, featuring a plot so knotty and strange even some members of the band didn’t understand it (“Ask Peter—I’m just the drummer,” shrugged Phil Collins when a journalist quizzed him about it shortly after release) and subject to one of the most famously theatrical live presentations in rock history. Some people think it presages the arrival of punk rock. In fact, there’s every chance that The Lamb Lies Down On Broadway is all those things—flawed experiment, career highlight, prog masterpiece, weirdly prescient precursor of punk—at once, which might account for its longevity.

The Lamb Lies Down on Broadway (50th Anniversary Super Deluxe Edition) arrives 4/28 via Rhino. You can pre-order it here.