The Duquesne University Tamburitzans, America's longest-running multicultural song and dance company, will present a free outdoor performance at Hartwood Acres at 7:30 p.m. Sunday. The outdoor amphitheater is off Middle Road in Hampton Township, Allegheny County. At Hartwood tonight, the Pittsburgh Ballet Theatre will perform Dwight Rhoden's "Step Touch" and George Balanchine's "Theme and Variations." Both these free shows are part of the Allegheny County Summer Concert Series. Call 412-350-2478 for more information.