The rock hall of fame is finally ready to roll.With fireworks and fanfare, Cleveland broke ground Monday for its Rock and Roll Hall of Fame and Museum, a project delayed for seven years by site changes, money problems and squabbling within the music industry. Hall of Fame inductee Pete Townshend of the Who said the museum poses the question, “What is this thing called rock and roll?” “It’s us!” someone in the crowd shouted back. “You know, you are right,” Townshend responded. “Thank you.” Other inductees at the groundbreaking for the $ 84 million music shrine included Carl Garner of the Coasters, Bill Pinkney of the Drifters, rhythm and blues performer Ruth Brown, Chuck Berry and Sam Phillips. Workers began clearing the lake shore plot in April, but the last piece of the financial puzzle fell into place only weeks ago, finally guaranteeing the hall would be built. The museum is designed by architect I.M. Pei. Clevelanders, ever sensitive about the city’s hard-to-kill image as the “mistake on the lake,” groused that the hall might never be built.