Celebrate the fifth anniversary of the Italian Baroque organ. Back by popular demand, this annual holiday concert features organ music by Jan Pieterszoon Sweelinck and Dieterich Buxtehude; improvisations on traditional German and Swedish carols for viola and organ; vocal music by Victoria, Lassus and Gombert; music for strings and sackbuts by Heinicken, de Salazar and Valentini; and a sing-along of holiday songs. The performers, from the Eastman School of Music, include Michael Unger and Steven Seigart, organ; Jenny Välitalo and Drew Vella, viola; vocal ensemble under the direction of Thatcher Lyman; Samuel Pierce-Ruhland, cello; Casey O'Neil and Nicholas Conn, sackbut; and Ulrika Davidsson, coordinator. Tickets are $10 (students $7), available from the RPO Box Office or at the door by cash or check. Seating is limited.