During the summer my parents went on a 3 week holiday across Scandinavia. When they were in Finland they visited the Santa Claus village at Lapland. If you send a letter to Father Christmas, that's where it ends up.
Once the letters have been opened and read the Stamp Club of Lapland package them together and sell them for charity. My Dad bought a pack and used them in this display as part of our Christmas decorations.
The envelopes are from children all over the world and it's interesting to see what Santa is called in different countries. It's also interesting to see how they addressed the letters. There's one that just says 'To Santa, Lapland' with a stamp, and it made it there. Amazing!