iHeartRadio Music Festival at Las Vegas Pictures of Lady Gaga, Jay-Z, Usher, Nicki Minaj, Ashley Greene

Las Vegas got even crazier this past weekend when the biggest names in music descended onto the property of the MGM Grand Hotel and Casino for the two-day iHeartRadio music festival. The good times kicked off on Friday with performances from Jay-Z, Coldplay, Alicia Keys, the Black Eyed Peas, Carrie Underwood, Bruno Mars, Kelly Clarkson and Jane's Addiction. Saturday night was just as star studded with energetic sets by Lady Gaga, Jennifer Lopez, Steven Tyler, Kenny Chesney, Nikki Minaj, Rascal Flats, Usher and Sting. Music artists weren't the only big names on hand — American Idol host Ryan Seacrest made the trip to the desert to MC the show and brought along girlfriend, and star of the upcoming dance film Footloose, Julianne Hough. Twilight star Ashley Greene was rolling solo to introduce Rascal Flats while Glee's Cory Monteith welcomed Sublime to the stage.