The Vatican will host its first-ever public concert on Sept. 13 in St. Peter’s Square, and the lineup is as unlikely as it is stacked: Pharrell Williams, Jelly Roll, Clipse, John Legend, Jennifer Hudson, Karol G, Teddy Swims, Angélique Kidjo and gospel choir Voices of Fire. Opera legend Andrea Bocelli will co-direct the concert alongside Pharrell. The concert is tied to the Jubilee Year and the Vatican’s World Meeting on Human Fraternity, which explains the unity-through-music theme. But the booking feels less like a symbolic move and more like a once-in-history experiment—what happens when a traditional faith meets pop, rap, gospel and opera? ET, and if you happen to be in Rome, admission is free—assuming you can wedge yourself into St. Peter’s Square.