Now, US rapper RZA is turning his hand to classical with a symphonic ballet.

He began working on the record during the pandemic, inspired by the discovery of an old Tommy Hilfiger book bag stuffed with notebooks he had filled over five years from the age of 14; lyrics on life and love as a teenage Robert Diggs, who grew up in the housing projects of Brownsville, in Brooklyn, New York, and later Staten Island.

There was a story to be told, he felt. The obvious thing to do would be to turn the words into rap, the music he is best known for. But it evolved into something new.

"I started reading through these lyrics and I'm recalling all the young love, the young exploration. The first time you had a drink or smoke. All this is written in my lyrics, like a lyrical diary... at first I thought I should rap it, right. Because I'm known as a rapper. But then I said, no, I should just write music to it."

Starting at his piano, the project became A Ballet Through Mud, a coming-of-age story told through music that delves into the complexities of love and the bonds of friendship - very different to the music most of RZA's fans will know him for. It was performed to a standing ovation by the Colorado Symphony Orchestra and dancers from the Alvin Ailey dance theatre school on stage in Denver 2023. Now, RZA is releasing the score as his first classical album.

"I think I've definitely been a guy that's pushing the boundaries and trying to surprise people," he says. "Definitely, you know, people would call it leftfield for me. But it's not, it's right in my alley." He describes the work as a "natural creative evolution" and says he has always been "fascinated" by classical music and composers, inspired by everyone from Mozart, Beethoven and Bach to Leonard Bernstein, Duke Ellington, Sergei Prokofiev - who wrote the children's symphony Peter And The Wolf - and Quincy Jones's collaborations with Frank Sinatra.

"Looking at Peter And The Wolf and knowing every character, every animal in that ballet or suite had an instrument to match to it - the flute was the bird, the trombone was the wolf... I started learning then that you can take instruments and give them characters," he says. "As a movie composer, that philosophy got reinforced."

The title, A Ballet Through Mud, is symbolic of his own life. He references his formative years in Staten Island, or Shaolin, as Wu-Tang rechristened it. "The mud is considered to be foul, dirty... you know, I'm RZA, I'm from the slums of Shaolin. But yet, out of the mud grows the lotus plant, considered pure, beautiful... so hopefully, you can go through the mud and come back up a lotus."

It tells the story of six young people with a theme of "youthful exploration", he says. "I thought about women in the sense of how men, that we are still kind of in the cave when it comes to our emotions, we're like cavemen." One of the characters isn't sure how to communicate with the girl he likes, he says. "It was from one of my lyrics... as a high school guy, I fell in love with some girl and was scared to tell her."

His fellow Wu-Tang Clan members are yet to hear the entire score, he says. "But we did a tour last year with Nas and if you came on my bus, you had to hear some [of this] music," he laughs. "But everybody who heard it, they said it sounds beautiful."

Of course, RZA isn't the first hip-hop star to embrace classical music. In July, Cypress Hill made their debut at the Royal Albert Hall in London, performing hits from their seminal album Black Sunday alongside the London Symphony Orchestra. That show happened to be inspired by an almost 30-year-old joke in The Simpsons, famous predictor of the future, but rappers B-Real and Sen Dog have long had classical influences.

"We started off as hip-hop artists, this is what we love to do, the roots of our existence," said B-Real ahead of the show. "But we've always challenged ourselves to be out of the box and do different things."

In recent years, ravers have also embraced the genre at classical tours by the likes of club favourites Ministry Of Sound and the Hacienda. And there has also been a metal crossover with the likes of Metallica performing releasing albums with the San Francisco Symphony - and even a Black Sabbath ballet.

RZA says there are parallels between hip-hop and classical. "If you listen to some of the Wu-Tang production you hear I bring in strings. You'll hear some of my production has incorporated classical samples." He cites famous examples of hip-hop sampling classical scores, such as Beethoven's Fur Elise in Nas's I Can.

The rapper began studying more himself when he scored his first film, Ghost Dog: The Way Of The Samurai, starring Forest Whitaker, released in 1999. He went on to score other films, including Quentin Tarantino's Kill Bill. "These types of ideas have been evolving in me through my progression of work," he says. "It's like it's in my blood now."

As we speak, RZA is working in post-production on his latest project, the upcoming film One Spoon Of Chocolate, which he has directed. Across music and film, he has never wanted to tie himself down to one genre or medium of art. In September, the Wu-Tang Clan play shows in Las Vegas - extra dates added to a residency billed as "more than a concert... a tribute to their prolific careers as individuals and as the most storied group in hip-hop history".

The most expensive album ever made

And earlier this year, their famous unique and rarely-heard 2015 record Once Upon A Time In Shaolin, the most expensive album ever made, made headlines once again as it went on display briefly as a piece of fine art in Australia. The album exists in a sole physical CD copy, created at the time as a statement on the value of music as streaming started to take over, and comes with a legal stipulation that the owner cannot publicly release the tracks until 2103.

The record was bought at auction for $2m (£1.5m at the time) by pharmaceutical executive Martin Shkreli in 2015, but was sold again by the US government to clear debts after he was jailed for defrauding investors. Earlier this year, about 500 fans got to hear the music - complete with a reported Cher cameo - at secret listening sessions.

It has been a wild journey. "Some of its journey has taken me by surprise and I think rightfully so," says RZA. "To me, that album has a life of its own and that's something I wanted for it, in all reality. It was a statement that was supposed to breed conversation. You know, should music be devalued? Is there more value on it when you can't have it? Is music really considered a serious form of art by today's society?

"Because it was like that as I was growing up... to get up and save my coins and then get on a bus and go to a record store and get it and read it, the cover, and open it and put it on, and to hold it... so you don't get fingerprints on it. It is something we value. And now it's more like swipe, swipe, swipe, swipe, swipe. I always said that it was similar to an Egyptian sceptre, something that belongs in museums and art galleries. It ended up there this year and that had nothing to do with me, you know. I heard that people came from around the world, they flew in to hang out, you know. And I wasn't even there. It's like my son right now. He's over in college right now, hanging out with his buddies, and I don't know what's going on, he's just having his own life."

There is a part of him that would love to still be involved in some way, he says. But that was never the point. "There's always a piece of me on anything that I've created or been part of that, you know, you want it kind of for yourself - but it don't belong to you. It's created for the world. And whoever gets a chance to hear it and enjoy it and create their own memories with it... those memories won't belong to me."

For now, though, he is concentrating on his classical work. He hopes it will inspire young children to learn instruments and feel "it's cool to grab that violin or oboe".

He continues: "It's a certain type of brain stimulation that comes from this type of music creation. Hip-hop and rock music, or just say today's music, has been able to be created on a computer, and that's great, that's the power of an orchestra in your hand." But knowing how to play an instrument, he adds, enables you to be "more elaborate, more communicative - not cookie-cutter".

And after A Ballet Through Mud, there is more to come, he promises. "I'm not going to stop here. I've already started writing something for the future that I'm also fascinated with."

You heard it here first. RZA, the hip-hop legend - now adding another string to his bow.