Nations often designate worthwhile items of cultural heritage or physical resource to be a "national treasure".
Ideally this means that people are then paid to preserve it and ensure that it remains a treasure for future generations as well.
In the country I live in we tend to go for works of art and countryside that exhibits great natural beauty.
I can't comment what it is for other places in the world, because I haven't visited many other places, but I can say that sometimes national treasures are alive...
What does your nation consider to be a treasure?