Classic hip-hop meets its rebellious younger sibling, when the Roots share the stage with Gym Class Heroes tonight at the Fillmore. Popular since the early '90s, the Roots have won countless awards, including a Grammy, for their urban rap. And, Gym Class Heroes' blend of hip-hop, R&B, and funk has topped Billboard charts. 7:30 p.m. Fillmore Auditorium, 1510 Clarkson St. $41. 303-830-8497, official website