U2's evolution into a great live band happened slowly. Listen to early live performances of late Seventies songs "Street Mission" and "Cartoon World" and it's stunning just how awful they were. In the early Eighties they toured clubs relentlessly, gradually becoming an incredible force onstage. When they graduated to the large theater on the 1983 War tour they were more than ready, and by 1987 they moved to arenas and stadiums. This summer they return to America on their massive 360 tour. Their record sales aren't what they used to be, but nobody sells more concert tickets or puts on a more epic show.