While in some cases Wikipedia is fine as a source, with population I highly recommend not using it. Especially considering that it says that Rome is larger in population than Milan. citypopulation.de is best for this, because even with countries Wikipedia considers places like Hong Kong as sorveign and you have to strictly sort through your data. But good idea, it just needs a better source.
Yeah, it was frustrating to miss all of those Belarusian cities due to spelling! I even checked on wikipedia how to spell them and the correct spellings weren't accepted.
I thought Turku was one of the larger cities in Finland. Also how on Earth can a country that is 1/8th the size of the city of Jacksonville, Florida, have 5 other cities bigger than the national capital? Doesn't seem possible. There's also the question of San Marino - a country 1/38th the size of Jacksonville - having multiple cities at all that seems ridiculous. Serraville is more like the small sub-development that the bus passes through on the way to the city center of San Marino than it is a city in its own right. I mean if that's a city then there are probably 3 cities in the gated suburban community where I live.
Turku is listed as the sixth most populated according to my source. I agree with you on San Marino though, those answers are municipalities. I will have them updated.
Turku is the third most populous urban area in Finland but only #6 city proper. The problem here is that Finnish cities actually municipalities, more like US counties: all of them (except maybe the capital) contain vast expanses of uninhabited land, and all major urban areas are spread across multiple "cities". Finnish "cities" #2 and #4 are suburbs of #1. Due to county mergers, "city" #5 is a dozen times bigger than Turku by land area, and slightly bigger by population.