If a stranger approached you at the British Museum in London or the Louvre in Paris, asked your nationality, and on hearing “American,” burst out in an enthusiastic rendition of “The Star-Spangled Banner,” would you be wary or alarmed, curious or pleased? Concord’s John Muresianu has been offering such spontaneous musical greetings to Concord’s international visitors for sixteen years, to near-universal acclaim—including a recent flattering profile on National Public Radio’s Weekend Edition.