Which monument in Oberndorf bei Salzburg is dedicated to a Christmas carol that Franz Xaver Gruber is best known for composing? 
Franz Xaver Gruber: Franz Xaver Gruber (25 November 1787 – 7 June 1863), was an Austrian primary school teacher, church organist and composer in the village of Arnsdorf, who is best known for composing the music to "Stille Nacht" ("Silent Night").
i don't know