no...no....that's the "HIGHWAY TO HELL" ...wrong song.

such a door for a similar opening at the bottom of one of our trees. He never got around to it, but it must be a common inspiration.

Here is a cool incarnation of the concept at Winterthur Estate and Gardens in Delaware:

And, at least in the past, if you leave the elf a note with the child's name on, there will be a reply in about a week in tiny 'writing' on a tiny slip of paper.