The Roman Catholic Archdiocese of Alba Iulia (); ) is a Latin Church archdiocese in Transylvania, Romania.
It was established as a bishopric, the diocese of Transylvania also called Erdély (in Hungarian), or Karlsburg alias Siebenbürgen (in German), in 1009 by King Stephen I of Hungary and was renamed as the diocese of Alba Iulia on 22March 1932.
It was raised to the rank of an archdiocese by Pope John Paul II on 5August 1991. It is exempt, i.e. directly subordinate to the Vatican, while the other Romanian dioceses form the Ecclesiastical Province of Bucharest.
The archdiocese covers Transylvania proper—the counties of Alba, BistriÃÂa-NÃÂsÃÂud, BraÃÂov, Cluj, Covasna, Harghita, Hunedoara, MureÃÂ, SÃÂlaj and Sibiu.
The cathedral episcopal see is St. Michael's, in Alba Iulia city. It also has a minor basilica in ÃÂumuleu Ciuc.
11% of its inhabitants are Roman Catholic, with concentrations in parts of Harghita and Covasna counties. Catholic adherents are predominantly ethnic Hungarians.