very strange - I just read the logs and I definitely found it in Schlosspark Laxenburg today!
I don't think that the others have been blind (altough it was quite a large box ;o) ) but I also can't imagine who would take the coin and then bring it back to the same location. very strange, indeed.
However - I guess the owner will take it as good news that it has appeared again, and I will take it with me to Italy or France next week.