In December 1918, Alba Iulia was officially declared Capital of the Great Union of Romania.

[8] The city administers four villages: Bărăbanț (Borbánd), Micești (Ompolykisfalud), Oarda (Alsóváradja), and Pâclișa (Poklos).

[14] Alba is the Romanian feminine form of the word for white, and Iulia ("Julius") refers to Gyula II, a mid-10th-century Hungarian warlord who was baptized in Constantinople.

[23][clarification needed] The first part of the name Alba denotes the ruins of the Roman fort Apulum, the pre-feudal white citadel.

[14][24] Later in the Middle Ages, different names were used: Frank episcopus Belleggradienesis in 1071, Albae Civitatis in 1134, Belegrada in 1153, Albensis Ultrasilvanus in 1177, eccl.

[23] The modern city is located near the site of the important Dacian political, economic and social centre of Apulon, which was mentioned by the ancient Greek geographer Ptolemy and believed by some archaeologists to be the Dacian fortifications on top of Piatra Craivii.

[26] Apulum was the largest urban centre in Roman Dacia and was the seat of the XIII Gemina Legion.

[30] After Stephen I adopted Catholicism, and the establishment of the Catholic Transylvanian bishopric, recent archaeological discoveries suggest that the first cathedral was built in the 11th century or possibly before.

In 1442, John Hunyadi, Voivode of Transylvania, used the citadel to prepare for a major battle against the Ottoman Turks.

During the reign of Prince Gábor Bethlen, the city reached a high point in its cultural history with the establishment of an academy.

The fortress Alba Carolina, designed by architect Giovanni Morando Visconti, was built between 1716 and 1735, at the behest of Emperor Charles VI of Habsburg.

Important milestones in the city's development include the creation of the Batthyaneum Library in 1780 and the arrival of the railway in the 19th century.

In October 2012, at the 90th anniversary of King Ferdinand's coronation, his great-granddaughter Princess Margarita of Romania visited Alba Iulia to commemorate the event.

The following year, the Ion Antonescu regime confiscated Jewish property and sent the men to forced labor.

The main historical area of Alba Iulia is the Upper Town region, developed by Charles VI, Holy Roman Emperor, in honour of whom the Habsburgs renamed the city Karlsburg.

The first monarchs of the Unified Romania, King Ferdinand I and Queen Marie were crowned in the cathedral on 15 October 1922.

The Unification Hall, also part of the National History Museum, retains historical significance from having hosted, on 1 December 1918, the rally of the 1228 Romanian delegations from Transylvania who determined the province's union with the Kingdom of Romania.

Foreign chronicles pictured it as an extremely luxurious building, richly adorned with frescos and marble stairs, which later deteriorated.

During the rule of Princes Gábor Bethlen and George II Rákóczi the second palace was restored, but not to its previous condition.

Alba Iulia is twinned with:[36] According to the 2021 census, there was a total population of 64,227 people living in this city.

At the 2011 census, there were 63,536 inhabitants; of these, 95.3% were ethnic Romanians, 3.2% Romani, 1.9% Hungarians, and 0.2% Germans (more specifically Transylvanian Saxons).