Very interesting !

Funny thing, in France we do use "up" and "down" but with a different set of axis. They don't represent north and south.

If you're in Lille (north of Paris), you'd say "I'm going up to Paris" although you'd be going south. If you're in Paris and you're going to Lille, you'd say "I'm going down to Lille" although you'd be going north. But if you're going to Lyon from Paris, you'd say "I'm going down to Lyon" and you would be going south.

In French you go "up" to the capital (or more generally to a larger city than you're currently in), and you go down from the capital (or more generally to a smaller city than the one you're currently in).

So you'd say from Paris "I'm going down to Lyon" or "I'm going down to Grenoble" and from Lyon you'd say "I'm going down to Grenoble" or "I'm going up to Paris". (And you instantly know that Paris is the largest city of the 3 and Grenoble the smallest ^^ so from Grenoble you go "up to Lyon" and "up to Paris").

I learned that fairly old because I didn't live in France until later in my childhood but I always found this linguistic kinda funny :)

Descendons donc en province, disent-ils a Paris !