Audioslave was formed after Zack de la Rocha left Rage Against the Machine and the remaining members were searching for another vocalist. Producer and friend Rick Rubin suggested that they should contact Chris Cornell. Boy that was smart!
Cornell was in the writing process of a second solo album, but decided to shelve that and pursue the opportunity to work with Tom Morello, Tim Commerford and Brad Wilk when they approached him. Morello described Cornell: "He stepped to the microphone and sang the song and I couldn't believe it. It didn't just sound good. It didn't sound great. It sounded transcendent. And... when there is an irreplaceable chemistry from the first moment, you can't deny it." The foursome wrote 21 songs during 19 days of rehearsal and began working in the studio in late May 2001.
They are one of the greatest bands ever brought together. Here's a tune I truly love called, Shadow On The Sun: