Medieval Golubac was built on the remains of an older Roman fortification. From 803 to 1018, this territory belonged to the First Bulgarian Empire, then to the Byzantine Empire until 1193, and to the Second Bulgarian Empire until 1257. Its good strategic position was recognized by medieval builders, who used the foundations of old fortifications to build new fortresses. It was constructed on the bank of the Danube at the very entrance to the Đerdap Gorge, on the rocks of Radan Hill. At this site stood the Roman fortress Vico Cuppe, and in the Middle Ages a new fortification was built here as a military fortress for close combat and an important strategic stronghold. Based on historical, architectural, and archaeological data, it is believed that the city was established in the second half of the 13th century to the early 14th century and built by the Serbs. Over time, the fortress’s main appearance changed, as it was repeatedly expanded and adapted to the needs of artillery, but it acquired its current form at the end of the 15th century.

Golubac is first mentioned in Hungarian sources dated 1335, 1337, and 1342 respectively. According to these sources, the fortress was associated with the Hungarian King Louis I. However, it is unknown when and by whom it was built, but its foundation, i.e., the "Upper Town," was built by a Serb, that is, an Orthodox nobleman, as evidenced by the Orthodox chapel in the fourth tower.

At the end of the 14th century, the Ottoman Empire conquered much of the Balkans and approached the southern borders of the Kingdom of Hungary. After the Battle of Kosovo Field (1389), the Ottomans began threatening Serbia as well. Therefore, in 1426, Serbian Despot Stefan Lazarević concluded an agreement with Hungarian King Sigismund of Luxembourg: the fortresses of Belgrade and Golubac were to be handed over to Hungary in exchange for protection of Serbia and recognition by the Hungarians of George Branković as Stefan’s successor. According to the 1426 treaty, the city was to be handed over to the Hungarians after the despot’s death (Stefan died in 1427) along with Belgrade. However, for unknown reasons, the city commander Duke Jeremiah handed it over to the Turks. Due to the strategic location of Golubac Fortress, Sigismund did not want to accept its transfer to the Turks. In the winter of 1427, he built the fortress of Laslovar (now Colonia, Romania) on the opposite bank of the Danube from Golubac. This fortress became the base for the campaign against the Ottomans. When the invasion began, Sigismund had about 15-20,000 soldiers. Sigismund’s army also included Lithuanian and Wallachian auxiliary regiments under the command of Zawisza Czarny and Dan II of Wallachia.

At the end of April, Christian forces attacked Golubac. For the first time in Hungarian military history, the Hungarian army used artillery in a military conflict. Soldiers shelled the fortress with guns from the Danube flotilla and from the walls of Laslovar. The Ottoman defenders of Golubac bravely resisted, but the shelling damaged the walls. Sigismund planned an assault, but at that moment a significant Ottoman army led personally by Murad II arrived. Sigismund decided to avoid battle and proposed a truce: the Christians ceased their attacks and began to retreat.

However, when the Christian army began crossing the Danube, the Ottomans, as always, broke the truce and launched a sudden attack. During the retreat, Sigismund’s personal guard commander István Rozgonyi and the commander of the Lithuanian contingent Zawisza Czarny, who covered the retreat of Hungarian and Wallachian troops, were killed. During the siege of the fortress in 1428, the Polish knight, diplomat, and hero of Henryk Sienkiewicz’s novels "The Teutonic Knights" and Andrzej Sapkowski’s "The Tower of Fools," Zawisza Czarny, who is considered a model of knightly honor, died. Zawisza Czarny is to Poles what Ilya Muromets is to Russians.

Until the 19th century, Golubac was ruled by the Turks. For some time it was held by the Austrians (1688-1690) and Serbian rebels during the Kočina Krajina and the First Serbian Uprising. The Serbs recaptured Golubac during the Second Serbian Uprising. Nevertheless, the city of Golubac was finally handed over to Serbian administration only in 1868. Then, along with some other Serbian cities, the Turkish garrison left the city in 1867, which was handed over to Serbian Prince Mihailo Obrenović.

The geometry of Golubac is irregular; it is consistently integrated into the terrain’s configuration. The fortress, carved into the rock, undoubtedly represents one of the most difficult obstacles for enemy invasions from the north. The highest points of the fortifications, the eastern and southern ones, were hard to reach due to the rocky terrain, and the easiest access was from the western side. Walls and towers were connected, and from each tower one could access the defensive wall. Golubac was protected by nine mainly square-shaped towers. In front of the lowest part of the fortification was a water moat, over which a bridge led through the gate into the city. The city had inner and outer fortifications.

Golubac is built in a fan shape and consists of three parts: the front, rear, and upper parts of the city (with the citadel). In total, it consists of 10 (9+1) towers and two large gates. Later, the towers were reinforced by the Turks, converted into artillery towers, and another tower was added around 1480. In front of the city is the front wall, forming the outer wall of the moat, which was probably filled with water and connected to the Danube. The city was connected by a heavy chain to Baba Kai Rock (which still protrudes from the water in the middle of the Danube), so it fully controlled both land and river traffic through the Đerdap Gorge. In front of the fortress was a civilian settlement, of which today only some partially explored buildings remain.

The front city consists of upper and lower parts, separated by a wall. The entrance is in the lower part, guarded by two artillery towers. At the end of the city is the last tower, added by the Turks as a low artillery tower. It controls the passage through the Danube and the approach to the city harbor; it is connected to the main fortress by a low wall. Opposite the entrance were transport gates leading to the rear city. On the wall separating the upper part from the lower, there are gates through which one can enter the Upper Town.

The rear city is separated from the Upper Town by a wall and a sharp rock 3 to 4 meters high. The entrance to the Upper Town is through gates, from which a road runs parallel to the wall to the entrance of the citadel.

Under this road are several buildings, between which a path descends through gates to the towers and wall above the Rear Town. In the rock on which the tower stands, a reservoir was carved, which was filled with rainwater. On the wall between the tower and the gates, there is a protruding terrace.

The citadel itself has a rectangular, almost square base, through which, between the outer wall and the rock on which the tower stands, runs a path to the last fortress—the donjon citadel. The last part of the path, less than a meter wide, is bordered by sharp rocks that on one side descend into the citadel about 5-6 meters below, and on the other side descend several tens of meters below, almost to the level of the Danube. A constant wind blowing through the gorge adds special charm to this passage.

The towers in the fort have wooden floors and stairs inside, while the stairs leading to them are stone. The width of the steps is less than 60 centimeters. Half of the towers are stone on all sides; the rest are stone on three sides, with the fourth side facing inward without stone. The donjon has an octagonal base, from which a round top rises, with a square interior in the center. Entry is through a door leading to a terrace protected by brackets, from which you enter the round part of the tower. Stone steps lead around the square interior to the top.

Many legends surround the fortress, the most popular of which says:

One legend says that the fortress was named Golubac (Dove City) because of the Byzantine princess Helena, who was imprisoned in the main tower. To ease her suffering and loneliness, the princess began feeding doves, which served as her messengers, hence the city’s name.

According to another legend, a beautiful Serbian princess was married to a fierce Turkish pasha commanding the fortress. The princess was secretly in love with a young man from a nearby village. Because of this betrayal, the pasha imprisoned the princess in the highest tower. The princess’s only friends in the cell were the doves she fed at the window. One morning, the Turk decided to end it all. He took her out of the dungeon, put her in a boat, and rowed to a rock in the middle of the river. He shackled her to the stone and shouted, "Baba kai!" which means "Repent!" He promised to return her to Golubac if she became a faithful wife. The princess did not repent. She remained tied to the rock, and the doves brought her food. Fishermen say the princess’s spirit still flies over the water’s surface, and the doves always come with food to the rock called Baba Kai.

There are also stories claiming the city was named for the shape of its towers, which resemble doves on the rock. Other legends say wild doves nested on the rocks, and the fortress was named after them.

Immediately after World War I, the main road was laid through the rock on which the fortress stands, passing directly through the fortress, using both the fortress’s carriage gates.

The main entrance gates were demolished; this road is the shortest connection between Serbia and the eastern parts of the Balkan Peninsula, so heavy trucks often passed through the fortress, barely able to get through the gates. Just before the fortress reconstruction, a new tunnel was built 20-30 meters outside the fortress, and the existing one was closed to traffic.

With the construction of the hydroelectric power plant on the Danube, its level near Golubac rose, so the lowest parts of the city were flooded. In years of severe drought or when the hydroelectric plant releases a large amount of water due to flood waves, one can enter a building deep in the city by boat, while at normal water levels, boats can barely pass through the arched remains of the building. The submerged parts of the walls along with the tenth tower offer great opportunities for passionate fishing enthusiasts, who are always found in the lowest parts of the fortress.

Thanks to its historical significance and exceptional architectural value, Golubac Fortress was declared a monument of exceptional importance in 1979. Scientific research and conservation work began in 1969 and were completed in 1987 due to lack of funding.

At the beginning of the 21st century, all parts of the fortification above the road, including the moat, were completely overgrown with nettles, blackberries, brambles, and similar vegetation, making movement along the upper parts of the fortification practically impossible except for a small narrow path leading to the Donjon towers. In spring 2005, measures were taken to remove this vegetation from the moats and suburban area. A renovated fountain was erected in the moat (previously hidden by tall vegetation) in honor of the Polish knight Zawisza Czarny.

In 2012, a project to revive the fort began, within which a bypass road and tunnel were built.

Sources:

https://en.wikipedia.org/wiki/Golubac_Fortress

https://sr.wikipedia.org/wiki/Голубачки_град

https://resolbi.ru/krepost-golubats-golubachka-serbia/