The nation announced the union of Transylvania with Romania here in 1599 and 1918, which were hugely important to Romanians. Alba Iulia was known by the Dacians as Apulum, serving both as the capital of Upper Dacia and, later, during Roman times, as the largest centre in the Dacian province of the Roman empire. From 1542 to 1690 Alba Iulia was the capital of the principality of Transylvania. Romania’s national day (1 December) is a time of major celebrations in Alba Iulia.