The Very Serious U2 of The Unforgettable Fire and The Joshua Tree would have had a hard time recognising the U2 of 1997’s Pop—an audacious exploration of dance and electronic music and nightlife that Achtung Baby and 1993’s Zooropa only winked at. The 1997-98 PopMart tour was a more absurdist and maximalist extension of Zoo TV’s sensory-overload commentary on commercialism—even if you couldn’t always tell which side of the commentary the kajillion-selling rock band was meant to be on. They wore fake muscles (except for drummer Larry Mullen Jr.; his were real). They performed under a golden arch with a giant mechanical lemon-shaped mirror-ball spaceship that the members would sometimes get trapped inside, Spinal Tap-style. U2 had never quite attempted anything like it before, or since, but you can relive the experience through the songs that made up the tour’s set list, which sprinkled classics like “Mysterious Ways” with a bit of glitter.