Marking its second post-comeback year, Music Midtown takes over Piedmont Park for two days (Sept. 21-22), ping-ponging performances by 15 acts, including: Avett Brothers, Florence & the Machine, T.I., Ludacris, Joan Jett & the Blackhearts, Girl Talk, Van Hunt, O'Brother, Adam Ant, and more. Friday night's lineup comes to a head when the Foo Fighters blaze through a marathon set of career-spanning highlights ("Monkey Wrench," "Learn to Fly"), along with a few covers. After walking away from the 2012 Grammy Awards with five wins, and soon after being declared Best International Group by the Brits (the British equivalent of the Grammys), it's been a banner year for the former Nirvana drummer-turned-frontman Dave Grohl and the rest of the group. If ever there were a time to see them live, this would be it. On Saturday night, Seattle's post-grunge torchbearers Pearl Jam bring it all to a close.