Yes there is another city. Its set up somewhere right between the boarder of Skyrim and Hammerfell.
This ^^
It tells you on one of the load screens during Skyrim. I think I read someone else's post on a previous thread mentioning that after the old Orsinium was destroyed, it was the Imperial legion that gave them safe passage and helped them to the new location.
I'm thinking it will be a possible future DLC for Skyrim as there is a large area misted over on the Skyrim map where this could be. The other area is to the east of Windhelm which could be Solstheim of the Dunmer & the Skaal Nords.
Is it just me, or is Orsinium the Tamriel version of Camelot?
"It is built on dreams. It will be destroyed, but it shall rise again and again, and again, and again - as long as the dream of Avalon remains true."
Was Camelot destroyed and rebuilt? I don't recall that. I think if there was a Camelot in Tamriel then it'll be in High Rock as that is the more Celtic influenced realm of Tamriel. Maybe the Direnni / Adamantine Tower as that is like a large castle. Daggerfall and Wayrest are cities so they wouldn't be.