Silent Night: The story of the Christmas carol
24 December 2013 Last updated at 00:01 GMT
Nearly 200 years ago, a priest living near the Austrian city of Salzburg, Joseph Mohr, wrote the lyrics to a new Christmas carol and asked schoolteacher Franz Gruber to set his words to music.
That carol was Silent Night - a festive favourite so popular around the world that it was declared an intangible cultural heritage by Unesco in 2011.
Now, many of the sites around Austria that are linked to the carol are welcoming tourists and a museum in the house where Gruber once lived has just been re-opened.
Bethany Bell has been discovering the story of Silent Night, in and around Salzburg.