The National Philharmonic Singers, under the direction of conductors Stan Engebretson and Victoria Gau, will present a free holiday concert at 8 p.m. Saturday at Christ Episcopal Church, 107 South Washington St., Rockville. The concert will feature famous carols, including Handel’s “Hallelujah Chorus;” Benjamin Britten’s “A Ceremony of Carols” with harp; John Rutter’s “Three Carols for Choir and Harp” and “The Blessed Son of God” from “Hodie” by Ralph Vaughan Williams. Additional highlights include music from various periods and a special audience sing along. Admission is free, but donations supporting the Community Ministries of Rockville will be accepted. For more information, please visit nationalphilharmonic.org.