Vidin (Bulgarian: Видин, pronounced [ˈvidin]) is a port town on the southern bank of the Danube in north-western Bulgaria. It is close to the borders with Romania and Serbia, and is also the administrative centre of Vidin Province, as well as of the Metropolitan of Vidin (since 870).
An agricultural and trade centre, Vidin has a fertile hinterland renowned for its wines.
A historical Romanian name of the city is Diiu.
Vidin is the westernmost important Bulgarian Danube port and is situated on one of the southernmost sections of the river. The New Europe Bridge, completed in 2013, connects Vidin to the Romanian town of Calafat on the opposite bank of the Danube. Previously, a ferry located 2 km (1 mi) from the town was in use for that purpose.
Vidin emerged at the place of an old Celtic settlement known as Dunonia. The settlement evolved into a Roman fortified town called Bononia. The town grew into one of the important centres of the province of Upper Moesia, encompassing the territory of modern north-western Bulgaria and eastern Serbia.
Vidin's main landmark, the Baba Vida fortress, was built in the period from the 10th to the 14th century. In the Middle Ages Vidin used to be an important Bulgarian city, a bishop seat and capital of a large province. Between 971 and 976 the town was the center of Samuil's possessions while his brothers ruled to the south. In 1003 Vidin was seized by Basil II after an eight-month siege because of the betrayal of the local bishop. Its importance once again rose during the Second Bulgarian Empire (1185–1422) and its despots were influential figures in the Empire and were on several occasions chosen for Emperors. From the mid 13th century it was ruled by the Shishman family.
By early 1290s Serbia expanded towards the vicinity of Vidin. Threatened by Serbian expansion, Shishman failed to repel the brothers forces, and accepted Serbian suzerainty. In practice, Shishman continued to be largely independent and dealt mainly with Bulgaria. Serbian suzerainty lasted until Serbian king Stefan Milutin´s death, in 1321. As Milutin left no testament, after his death, in Serbia occurred a period of civil war with Stefan Dečanski, Stefan Konstantin and Stefan Vladislav II fighting for power. Shishman took advantage of this situation, set free from Serbian rule, and returned to the Bulgarian sphere. In 1323 Shishman was chosen to be the Bulgarian tsar. Shishman made an anti-Serbian treaty with the Byzantines, however, after Serbian victory over Bulgarians in the Battle of Velbazhd in 1330, Bulgaria lay militarily crippled and politically subordinated to Serbia's interests.
In 1356, Bulgarian Tsar Ivan Alexander isolated Vidin from the Bulgarian monarchy and appointed his son Ivan Stratsimir (1356–1396) as absolute ruler of Vidin's new city-state - the Tsardom of Vidin (Bdin / Badin).
In 1365, the Tsardom of Vidin was occupied by Magyar crusaders. Under Hungarian rule, the city became known as Bodony, but the occupation was short-lived. In 1369, the Second Bulgarian empire drove out the Hungarian military, but in 1396 Vidin was occupied by a foreign force again.
In 1853, The Times of London reported that Widdin, as it was called, was
a considerable town, with a population of about 26,000, and a garrison of 8,000 to 10,000 men. Widdin is one of the important fortified places of the military line of the Danube. It covers the approaches of Servia, commands Little Wallachia, the defiles of Transylvania, and, above all, the opening of the road which leads through Nissia and Sophia on to Adrianople. Its form is an irregular pentagon; it is strongly bastioned, possesses a fortified castle, with two redoubts in the islands, and its defences are completed by an extensive marsh.
In 1859 the English traveler Samuel Baker happened to visit Vidin and spotted the 14-year old Romanian Florence Barbara Maria von Sass being sold into slavery, by some accounts destined to be owned by the Pasha of Vidin. Baker redeemed her and took her with him, she eventually became Florence Baker, his wife and partner in the exploration of Africa  .
During the Serbo-Bulgarian War (1885), the town was besieged by a Serbian army.