Kenny Chesney, Carrie Underwood and Rascal Flatts will perform this weekend at the first-ever iHeartRadio music festival which begins Friday (Sept. 23) in Las Vegas. The two-day festival will also feature the Black Eyed Peas, Kelly Clarkson, Coldplay and Lady Gaga, among many others. Hosted by Ryan Seacrest, the festival will take place at the MGM Grand Garden Arena. The event will stream live online and via mobile devices at IHeartRadio.com. Underwood and Clarkson will appear on Sept. 23, while Chesney and Rascal Flatts will perform on Sept. 24.