Really? Solitude's bigger than Daggerfall?
Huh. I guess the Nords never struck me as the cosmopolitan type.
Solitude is supposed to be one of the largest cities in the empire.....
Tamriel is about the Size of Europe(Europe is a bit smaller)...
Yokuda was supposed to be much larger than Tamriel..
Atmora is essentially the Artic about the same size I reckon.
Pyandonea is about the size of Smmerset Isles so I'd say about 1.8-2 million sqkm
Akavir is about the size of Tamriel or slightly smaller.
So considering the distances between the continents and the considerably large seas and oceans...I'd say that nirn is about he size of Mars or at most the size of Venus(just slightly smaller than earth).