Sorry for the bad title. Anyways... we've all heard of the Skyrim loading screen that mentions Orsinium being on the border between Hammerfell and Skyrim. That loading screen could be interpreted as "Orsinium is on the hammerfell side, near the border", or "orsinium is up in the mountains between the two provinces", but could it be that Orsinium actually just bleeds into both Skyrim and Hammerfell? That said, I've noticed that along the border with Hammerfell, there is a concentration of orc settlements, higher than anywhere else. These are http://www.uesp.net/wiki/Skyrim:Cracked_Tusk_Keep, http://www.uesp.net/wiki/Skyrim:Bilegulch_Mine and of course, http://www.uesp.net/wiki/Skyrim:Dushnikh_Yal. Do you think this is what Orsinium actually looks like? Is Orsinium not just a city, but a collection of orcish settlements spread out in a certain area?

Doubtful. You'd think the locals and Orcs themselves would have referred to the collective strongholds as such. It just seems like to big a detail to wash over.

Interesting. Orsinium used to be a city. It's possible that today it reformed and became a collection of smaller settlements, though it seems more likely that it's still both a city and an area filled with Orc strongholds. I'd be surprised if it didn't have any administrative center. In any case, I'm sure that its inhabitants would proudly inform us that they're a part of the Orcish independent state. Orcs in the settlements you listed don't mention anything about it, and as Dargor said, it's too important to skip without a word. I'm inclined to believe that we may have been close to Orsinium's (area) border, but Orsinium (city) is hidden deeper in the mountains.