LONDON: It’s only rock ‘n’ roll — but it isn’t, is it?

The music business is about commerce as well as entertainment, and the Rolling Stones are one of its biggest multinational firms. There’s plenty of both art and business in “Exhibitionism,” a vast exhibition that covers 20,000 square feet of London’s Saatchi Gallery with five decades of Stones history.

The more than 500 artifacts, borrowed from the band’s archive and private collectors, include musical instruments, lyrics, sketches, film clips, outfits, posters, album artwork and stage designs. There is even a fake donkey. From entertaining to excess, the Stones rarely do things on a small scale.

“In the end, we had over 25,000 things to choose from,” said Australian rock promoter Tony Cochrane, the show’s executive producer.

“I knew the Rolling Stones had a warehouse where they had kept a lot of their personal artifacts, memorabilia, famous instruments and the like,” he said Monday, a day before the show’s public opening. “But no one could have known how enriched the collection was.”

The result is a treasure trove for fans, who can ogle everything from a marabou-feather cape Mick Jagger wore to sing “Sympathy for the Devil” to a Maton guitar owned by Keith Richards whose neck fell off during the recording of “Gimme Shelter” (the song ends with a barely audible clunk).

Even casual fans will likely be impressed by the exhibition’s attention to detail. It opens with a life-size recreation of an apartment the band members shared in 1962-63 in Chelsea, a then-raffish, now-affluent London neighborhood.

“It was a hovel,” Richards says on a recording, and the recreation captures the peeling wallpaper, mold-stained walls and unmade beds, the dirty dishes, empty beer bottles, broken eggshells and overflowing ashtrays. It even smells.