The first documentary mentioning of the name of the town (Varadinum) shows up in 1113 though it seems that its foundation has been set on the bank of the Crişul Repede River, a long time before that year.
In 11th century, King
Ladislas the First (1077 – 1095) built a fortified monastery with
Virgin Saint Mary as patron. Later, he lays the foundations of the Roman-Catholic Bishopric of Oradea within the fortress. In June 27, 1192, Pope Celestinus III sanctified King Ladislas I. This act and the very occasion made the fortress a continuously prestigious pilgrimage place. Between 11th – 12th centuries, the fortress was a fortification (castrum), made from earthen walls and stockade, some stone walls and several wooden watch towers at the gates and the corners of the inner fortress.
In 1241, Master Ruggero di Puglia describes in the famous poem
Carmen miserabile the conquest and setting on fire of Oradea Fortress, during the Tartar-Mongolian invasion. In February 1245 was the sequel to the Lyon Council – where the draft of a coherent policy of Catholic states against the Tartar threat is put forward – a wide reconstruction process starts in Oradea as well, thanks to a series of facilities given to the city. Around 1290, Roland, son of Toma - from the ruling family known as Borşa of Transylvania – has a family conflict with the royalty, to which the bishops of Bihor were loyal. As a result, he attacks the fortress under reconstruction and causes great damages.
The new medieval fortress, in heptagonal shape, was erected in 14th century; the precinct was irregularly towered and embattled. The gate was protected with two solid towers; to the south, a Gothic Bishopric Palace was erected, whose outer wall is also a siding. On the south-western side of the wall is found the second entrance to the Fortress. An impressive Gothic cathedral was erected between 1342 – 1370, with three aisles and an octagonal altar, a facade with two towers and massive abutments; ample decoration work is done inside and various altars are built.
Between 1360 – 1370, brothers Martin and George from Cluj build the statues of the three Canonized Hungarian kings: Stephen I, Ladislas I and Emerick. They will remain inside the Fortress. In May 20, 1390, the same sculptors uncover the equestrian statue of King Ladislas I, in natural size and entirely gilded, erected at the order of King Sigismund of Luxembourg (1387 – 1437). In August 25, 1401, Pope Bonifacius IX confers a privilege to the fortress cathedral, bringing it to the same rank as San Marco Church of Venice and Santa Maria Portiuncula of Assisi. Thus, the cathedral becomes a pilgrimage place for Christians from all over Europe.
In 1427, the Oradea fortress Bishopric had its own corps of troops (banderia), which consisted of 500 riders and as much infantry, recruited especially from among Romanian kings of Bihor County. The bishops Giovanni de Dominis da Arbe, leader of Varna Crusade (1444) and Perenyi Ferenc (Mohacs Battle, 1526) fell on the battlefield leading this corps. For two weeks, around Easter (March 1412), King Vladislav Jagello of Poland, accompanied by King Sigismund of Luxembourg, arrive to the fortress. Their close relationship was also facilitated by Mircea cel Bătrân, King of the Romanian Country.
Between 12th – 15th centuries, 7 royalties are buried inside the cathedral or in its churchyard: King Ladislas I, Andrew II, Stephen III, Ladislas IV the Cuman, Queen Beatrix, Queen Mary, and Sigismund of Luxembourg - Hungarian King and German Emperor. In 1367 follows Elisabeth, wife of Duke Ladislas of Opulia, the Paladin of Hungary, daughter of Nicolae Alexandru Basarab.
In 14th–15th centuries, the bishops of Oradea fulfill diplomatic assignments for Hungarian Kings at various European courts, such as: Andrew Bathori (1329 – 1245) for King Charles Robert of Anjou in Italy, at the Naples court (1333); Demetrius (1345 – 1372) for King Louis the Great at the Romanian Country kingly court - Nicolae Alexandru Basarab and in Italy at the Naples court; John Filipecz Pruis for King Matia Corvin in Italy, at Naples (1476), Urbino and Rome (1482), Milan (1487).
In 15th century was the „Golden Age” of the fortress, as it becomes an important center of Humanism and Renaissance in Central and Eastern Europe. The most important bishops of the time were Andrea Scolari, also known as „The Florentine” (1409–1426), John Vitez of Zredna (1444–1465) and Sigismund Thurzo (1506–1512). The illustrious physicist of Vienna university, Georg Peuerbach (1423-1461), builds an astronomic observatory in Oradea and, establishing the zero meridian here, calculated the sun and moon eclipses in his work, “Tabulas Varadienses”. The Canonical lecturer Vepi Peter reorganized the Capitular School of Oradea (1439–1440) and created a foundation for its students.
In February 7, 1474, the Pasha of Simendria, Ali Oglu Malcovici, perform a rapid attack on Oradea Fortress in the winter, robbing it without notice.
Gheorghe Doja's rebels armies attacked the citadel (1514) but failed to occupy it, thanks to the incoming support of the captain of the city of Făgăraş, Tomori Pál.
After the fall of the feudal Hungarian Kingdom and its division between Turks and Hapsburg, Oradea fortress was disputed (1526-1538) between Ferdinand of Hapsburg, self-declared King of Hungary, and King John Zapolya. The peace of Oradea (February 24, 1538), was the first international treaty that consecrated total separation of Transylvania from Hungary. In April 10, 1557, the fortress of Oradea was retaken from the Hapsburg by the army of Principality of Transylvania, led by Tamás Varkocs, with a mission to defend the western border of the Principality.
The political and military climate in Central Europe have imposed the building of a new fortification, adapted to the military needs. The Transylvanian princes employed Italian military architects, who produced the new pentagonal fortress, with towers on corners and defensive ditch water, in later Renaissance style.
During the Ottoman siege (September 25 to November 3 1598), Michael the Brave sent a detachment of 1500 horsemen led by Aga Lecca in support of Oradea Fortress. The Hapsburg sent also a detachment of about 2000 infantry man and 500 cavalry under General Melchior von Rodern. The Vienna Imperial Court recognized Bocskai István as Prince of Transylvania and yield it the Oradea Fortress (June 23, 1606).
After a difficult siege, which lasted 46 days (August 27, 1660), with a report of 45,000 Turkish forces against 850 defenders, due to a betrayal, the Ottomans take Fortress of Oradea and installed here the headquarters of a Pasha, that will last for 32 years. Count Ladislaus Rakoczi attacked by surprise the citadel in May 1664, in the market day, with 200 soldiers disguised as peasants, but the attempt failed when Rakoczi was shot on city walls. The Imperial army encircle the fortress and begins a long siege (July 1691-28 May 1692), completed by the surrender of the Ottoman garrison to General Donath Heissler. Between 1692-1695, the fortress was rebuilt after the plans of military engineer Baron Ernst von Borgsdorf. In the Autumn of 1693, an auxiliary group of Tatars of the Ottoman army led by grand vizier Mustafa Bozuklu tried unsuccessfully to capture the garrison of Oradea in a surprise raid.
Between 1703-1710, the Oradea fortress was unsuccessfully besieged during the conflict between rebels led by Francis Rakoczi II and Hapsburg. In 18th century, although the citadel was only a military garrison, the Austrians will continue to pay attention and to undertake major repairs and refurbishments campaigns in 1725, 1754-1755 and 1775-1777, the last finalizing all the architecture that can be visited today.
In 1793, in the fortress were imprisoned 450 French prisoners. In 1836, a great fire destroyed much of it. During the Revolution of 1848-1849, the fortress was an important headquarter of the revolutionaries. In May 16, 1857, Emperor Franz Josef I canceled by decree the military status of the fortress, but will continue to be used as auxiliary military objective and will receive compensation in the years 1883-1887.
Between WWI and WWII, it was the seat of a police school. In 1947-1952, was used as a transit (the northern wing). Between 1945-1989, the fortress was still a military objective, used both by the Ministry of Interior and the Ministry of Defense. Unfortunately, the process of degradation continues now and the authorities need substantial funds for restoration.