The romantically nihilist heart of Head-On fluttered to punk and Turkish folk, seemingly contradictory genres that both sang the song of amour fou. Fatih Akin’s rich documentary follow-up, Crossing the Bridge, digs deeper into Istanbul’s musical and social history. The project began when Alexander Hacke, bassist for German avant-everything band Einstürzende Neubauten, worked on Head-On‘s soundtrack and was bewitched by the local sounds. The film follows him on his return trip as he records every tune he stumbles over. In briskly edited sequences peppered with fascinating found footage, each genre is tightly linked to a neighborhood. The grunge kids ape Nirvana in gentrifying Beyoglu, hip-hop takes baby steps in quaint Kadiköy, and clarinetist Selim Sesler drops jaws in a rural bar in Kesan. There is a general fear among the film’s subjects that local traditions are dying amid the rush to modernization. This uncertainty is rendered sublime by national icon Sezen Akzu in her command performance of “Memories of Istanbul,” evoking the city’s rapidly disappearing past with impossibly noble resignation.