No offense to the folks at 106 & Park, but upper Manhattan’s hip-hop story truly begins with the Harlem World Cultural Entertainment Center & Disco. From 1978 until 1984, now-legendary names like Doug E. Fresh, Kool Moe Dee, Chief Rocker Busy Bee and New Edition cut their teeth and staged rap battles at the West 116th Street venue; the club was also a nighttime refuge from the violence and drugs that gripped much of the neighborhood at the time. For “Harlem World: Throw Ya Hands in the Air,” former co-owner Chuck Foster has loaned around 400 performance photos and snapshots of venue regulars, displayed alongside videos of landmark moments like Kool Moe Dee’s epic battle with Busy Bee. Move over, Soul Train, this was the real heart of the IRT. Through June 25.