Friday-Saturday: In sound and ambition, Coldplay always seemed geared to arenas. Arguably the defining band of this century, the British rock quartet has a repertoire stocked with anthems. Frontman Chris Martin is an energetic, infectious cheerleader, and the band has more fan-friendly gimmicks than Flaming Lips. Spoiler alert: Coldplay gives each concertgoer a bracelet, which the band lights up from the stage during the concert -- blinking in beat to the music. And it's recyclable. Talk about "Viva la Vida." These St. Paul shows will be the final two on Coldplay's North American leg of the Mylo Xyloto Tour, which started in April. Opening are Charli XCX and Marina and the Diamonds. (7 p.m. Fri.-Sat. $47.50-$97.50. Xcel Energy Center, W. 7th St. and Kellogg Blvd., St. Paul. 1-800-745-3000, or