Old Bar, the biggest urban entity in ruins in Montenegro, is situated 3.5 km northeast of New Bar.

Old Bar was first documented in the 10th century as Antibareos, but the settlement is assumed to have existed at this site even earlier and it was mentioned as a rebuilt Roman castrum in the 6th century. Until the mid 11th century, it was ruled by the Byzantium, and from 1042 onwards, it entered the constitution of the Slavic Zeta. In Bar, in 1067, Mihailo, the ruler of Zeta, was proclaimed a king. In 1089, under king Bodin, the bishopric of Bar was raised to the rank of an archbishopric. From 1160 to 1183, Bar was ruled by the Byzantium again, and from 1183 up to the 14th century, it constituted part of the Nemanjic state. For a brief period, it was ruled by the Balšics. It was subjugated by Venice in 1443 and ruled until overthrown in 1571 by the Turks, in whose domain it remained until 1878, when the Montenegrins liberated it. In the last battles, many town buildings were badly damaged and brought to ruins. Since that time, the town has not been reconstructed and people have moved to a suburb below.

The furthest northern part of the original medieval Bar was occupied by a powerful fortress known as Tatarovica. The town was entered through two gates, which, together with the towers, belong to the oldest period of the town's existence, from the 9th to 11th century. The latest expansions of the town were done during the 15th and 16th centuries, under the Venetian rule. Unlike the previous medieval walls, which had been high and thin, the walls constructed during the Venetian time were lower and thicker with oblique external sides (escarpments), powerful corner towers-bastions intended to accommodate cannons and a strong entrance gate. This manner of construction is adjusted to the use of firearms and a new military technology.

The existing street network consists of narrow, winding streets, very often adjusted to the terrain configuration. In the oldest part, a certain regularity of streets can be discerned which might be remnant of an eventual antique or later system of orthogonal streets. In front of important sacral objects, several squares have been formed, usually of irregular foundations.

There were several bigger medieval sacral object in Old Bar, the most outstanding being: the Church of St. Theodora (9th – 11th c), reconstructed into the Church of St. George during the 12th and 13th century; the 13th -century Church of St. Nicolas' i.e. St. Mark's; the Church of St. Veneranda from the 14–15th century; the 14th-century Church of St. Catharine built above an arch spanning the street.

Residential buildings were built at short distances from one another, forming thus bigger blocks. Objects were built of hewn stone, usually as one-storeyed buildings, although it is possible to find some more-storyed ones. In a ground level, there was usually a konoba, entered from the street. If a building contained a water cistern, it was usually placed below the konoba level. The upper storeys had separate entrances with stairways. Roof was usually covered by shingle and slate.

The town also had bigger palaces of public and social importance, such as the Municipal Palace, the Ducal Palace, etc. The palaces are characterized by architectural details belonging to different styles, beginning with the late Gothic and Renaissance to typically oriental motifs. Some public buildings were constructed during the Turkish time: a Turkish bath (hammam), a gunpowder magazine and a clock tower.