“Twenty years ago, as mortar shells began raining down on Sarajevo, killing his friends and neighbors, Vedran Smajlovic did what he knew best to help the city: he played his cello at funerals, in bomb shelters and in the streets.” This week, to mark the 20th anniversary of the Serbs’ siege of the city, Smajlovic performed there for the first time since the end of the war.