<P> Wise also spent considerable time and effort on casting the secondary characters . For the role of Max Detweiler, Wise initially considered Victor Borge, Noël Coward, and Hal Holbrook among others before deciding on Richard Haydn . For the character of Baroness Elsa Schraeder, Wise looked for a "name" actress--Andrews and Plummer were not yet widely known to film audiences--and decided on Eleanor Parker . The casting of the children characters began in November 1963 and involved over two hundred interviews and auditions throughout the United States and England . Some of the child - actors interviewed or tested, who were not selected, included Mia Farrow, Patty Duke, Lesley Ann Warren, Geraldine Chaplin, Shelley Fabares, Teri Garr, Kurt Russell, and The Osmonds . Most of the actors selected had some acting, singing, or dancing experience . Charmian Carr, however, was a model who worked part - time in a doctor's office and had no ambition to pursue a career as an actress . After a friend sent her photo to Wise's office, she was asked to interview . Wise later recalled, "She was so pretty and had such poise and charm that we liked her immediately ." The last person to be cast was Daniel Truhitte in the role of Rolfe . </P> <P> Rehearsals for the singing and dance sequences began on February 10, 1964 . The husband - and - wife team of Marc Breaux and Dee Dee Wood, who had worked with Andrews on Mary Poppins, worked out the choreography with Saul Chaplin on piano--the arrangements could not be altered under Rodgers and Hammerstein's contract . The stage choreography was not used because it was too restrictive . Breaux and Wood worked out all new choreography better suited for film that incorporated many of the Salzburg locations and settings . They even choreographed the newly added puppet dance sequence for "The Lonely Goatherd". The choreography for the Ländler strictly followed the traditional Austrian folk dance . The musical arranger Irwin Kostal prerecorded the songs with a large orchestra and singers on a stage prior to the start of filming . In her book, The Sound of Music: The Making of America's Favorite Movie, Julia Antopol Hirsch says that Kostal used seven children and five adults to record the children's voices; the only scene where the child - actors actually sing is when they sing "The Sound of Music" on their own after Maria leaves . Charmian Carr refuted the claim that the voices of the child actors were dubbed in the film and on the soundtrack . Carr contended that all of the children who are in the film sing on the track, but four other children were added to most of the songs to give them a fuller sound, they did not replace them as singers . The voices of some of the adult actors had voice doubles, including Peggy Wood and Christopher Plummer . </P> <P> Principal photography began on March 26, 1964 at 20th Century Fox studios in Los Angeles, where scenes from Maria's bedroom and the abbey cloister and graveyard were filmed . The company then flew to Salzburg where filming resumed on April 23 at Mondsee Abbey for the wedding scenes . From April 25 through May 22, scenes were filmed at the Felsenreitschule, Nonnberg Abbey, Mirabell Palace Gardens, Residence Fountain, and various street locations throughout the Altstadt (Old Town) area of the city . Wise faced opposition from city leaders who opposed him staging scenes with swastika banners . They relented after he threatened instead to include actual newsreel footage of crowds cheering Hitler during a visit to the town . On days when it rained--a constant challenge for the company--Wise arranged for scenes to be shot at St. Margarethen Chapel and Dürer Studios (Reverend Mother's office). From May 23 to June 7, the company worked at Schloss Leopoldskron and an adjacent property called Bertelsmann for scenes representing the lakeside terrace and gardens of the von Trapp villa . From June 9 to 19, scenes were shot at Frohnburg Palace which represented the front and back façades of the villa . The "Do - Re-Mi" picnic scene in the mountains was filmed above the town of Werfen in the Salzach River valley on June 25 and 27 . The opening sequence of Maria on her mountain was filmed from June 28 to July 2 at Mehlweg mountain near the town of Marktschellenberg in Bavaria . The final scene of the von Trapp family escaping over the mountains was filmed on the Obersalzberg in the Bavarian Alps . </P> <P> The cast and crew flew back to Los Angeles and resumed filming at Fox studios on July 6 for all remaining scenes, including those in the villa dining room, ballroom, terrace, living room, and gazebo . Following the last two scenes shot in the gazebo--for the songs "Something Good" and "You Are Sixteen"--principal photography concluded on September 1, 1964 . A total of eighty - three scenes were filmed in just over five months . Post-production work began on August 25 with three weeks of dialogue dubbing to correct lines that were ruined by various street noises and rain . In October, Christopher Plummer's singing voice was dubbed by veteran Disney playback singer Bill Lee . The film was then edited by Wise and film editor William Reynolds . Once the film was edited, Irwin Kostal, who orchestrated the musical numbers, underscored the film with background music consisting of variations on Rodgers and Hammerstein's original songs to amplify or add nuances to the visual images . When dubbing, editing, and scoring were complete, Wise arranged for two sneak - preview showings--the first one held in Minneapolis on Friday January 15, 1965 at the Mann Theater, and the second one held the following night in Tulsa . Despite the "sensational" responses from the preview audiences, Wise made a few final editing changes before completing the film . According to the original print information for the film, the running time for the theatrical release version was 174 minutes . The film was eventually given a G rating by the Motion Picture Association of America . </P>

Where was the opening scene of the sound of music filmed