alba_iulia | ispartof | alba_county <sep> alba iulia (romanian pronunciation: [ˌalba ˈjulia] (listen); german: karlsburg or carlsburg, formerly weißenburg; hungarian: gyulafehérvár; latin: apulum) is a city that serves as the seat of alba county in the west-central part of romania located on the mureș river in the historical region of transylvania, it has a population of 63,536 (as of 2011)during ancient times, the site was the location of the roman camp apulum since the high middle ages, the city has been the seat of transylvania's roman catholic diocese between 1526 and 1570 it was the capital of the eastern hungarian kingdom from which the principality of transylvania emerged by the treaty of speyer in 1570 and it was the capital of the principality of transylvania until 1711 at one point it also was a center of the eastern orthodox metropolitan of transylvania with suffragan to vad diocese 
alba iulia os part of the county of alba.alba iulia serves as the seat of alba county in the west-central part of romania