Bari is the capital city of the province of Bari and of the Apulia region, on the Adriatic Sea, in Italy. It is the second most important economic centre of mainland Southern Italy after Naples, and is well known as a port and university city, as well as the city of Saint Nicholas. The city itself has a population of about 320,500 over 116 km2, while the fast-growing urban area counts around 653,000 inhabitants over 203 km2. 

Bari is made up of four different urban sections. To the north is the closely built old town on the peninsula between two modern harbours, with the splendid Basilica of Saint Nicholas, the Cathedral of San Sabino (1035–1171) and the Swabian Castle built for Frederick II, which is now a district known for it's nightlife. To the south is the Murat quarter, the modern heart of the city, which is laid out on a rectangular grid-plan with a promenade on the sea and the major shopping district.

Modern residential zones surround the centre of Bari, the result of chaotic development during the 1960s and 1970s replacing the old suburbs that had developed along roads splaying outwards from gates in the city walls. In addition, the outer suburbs have developed rapidly during the 1990s. The city has a redeveloped airport named after Pope John Paul II, Karol Wojtyla Airport, with connections to several European cities.

After the devastations of the Gothic Wars, under Lombard rule a set of written regulations was established, the Consuetudines Barenses, which influenced similar written constitutions in other southern cities.

Until the arrival of the Normans, Bari continued to be governed by the Byzantines, with only occasional interruption. Throughout this period, and indeed throughout the Middle Ages, Bari served as one of the major slave depots of the Mediterranean, providing a central location for the trade in Slavic slaves. The slaves were mostly captured by Venice from Dalmatia, the Holy Roman Empire from what is now Prussia and Poland, and the Byzantines from elsewhere in the Balkans, and were generally destined for other parts of the Byzantine Empire and (most frequently) the Muslim states surrounding the Mediterranean.

For 20 years, Bari was the center of the Emirate of Bari; the city was captured by its first emirs Kalfun in 847. The city was conquered and the Emirate extinguished in 871, due to the efforts of Emperor Louis II and a Byzantine fleet. In 885, Bari became the residence of the local Byzantine governor and a failed revolt (1009–1011) of the Lombard nobles Melus of Bari, against the Byzantine governorate, though it was firmly repressed at the Battle of Cannae it offered their Norman allies a first foothold in the region. In 1025 Bari became attached to Rome and was granted "provincial" status.

In 1071, Bari was captured by Robert Guiscard, following a three year siege. Bari was occupied by Manuel I Komnenos between 1155–1158. In 1246, Bari was sacked and razed to the ground and the King of Sicily, repaired the fortress of Baris but it was subsequently destroyed several times. Bari recovered each time.