[cameldrv]

I don’t know what’s usual in France, but it’s usual in Germany for apartments to not have numbers. You have to put your name on your mailbox, and there’s no way to address something to someone who doesn’t live in the apartment. If you’re filling out government forms, you sometimes have to put in something like “third floor left side” so they know where you actually live.

[jll29]

Britain also has "dwelling designations" like "3FL" (third floor left) commonly used to describe unnumbered flats (which may well have numbers or not). I suspect this way of referring to flats is unofficial, but it is commonly seen on letters.

[growse]

Same in Iceland I think. No name on the door? No mail.

[dhosek]

Costa Rica doesn’t have numbers on the buildings, and many streets lack street signs, if not names. You’ll have addresses like “50 meters north of the old church” or “behind the banana stand.”¹