Athens, the city that symbolized the classical world, was throughout the medieval period a small provincial town in the Byzantine Empire to which the sources rarely refer, and then only coincidentally. Its history from the end of the sixth century to the Turkish conquest of 1456 can be divided into three periods: the Dark Ages (7th–9th centuries), when life in the city continued but was confined to a small area around the Acropolis; the middle Byzantine period (10th–12th centuries), when Athens grew and can truly be said to have flourished (as witnessed by the large number of churches built during this time); and the period of Frankish rule (13th–15th centuries), under the rule, successively, of French, Catalan, and Italian dukes, when the Acropolis was converted into a medieval castle and the city shrank to a settlement huddled at the foot of the rock.
In the late Roman period, Athens had flourished for the last time as one of the empire’s centers of education and as the focus for the development of Neo-Platonic philosophy. It can be deduced from the sources and from the finds of excavations that the Greco-Roman tradition and the slowly emerging Christian world coexisted peacefully in Athens to the late fifth century. When Justinian closed the schools of philosophy (in 529), Christianity gained the upper hand in Athens, and the city could now clearly be seen to be in decline. In the late sixth century, and throughout the seventh century, the ancient temples - the Parthenon, the Erechtheion, the Temple of Hephaestus - were converted into churches. A raid by the Slavs (dated to 582) struck yet another blow at the city. 
During the two centuries that followed, we have little historical testimony to the fate of Athens, and excavations have yielded only scanty finds. The demographic shrinkage and the restriction in urban economic activity by which the provincial cities of Byzantium were hit in the seventh and eighth centuries can be perceived in Athens, too. Throughout that period, the city was confined to a small part of what had once been its area, that is, within the narrow bounds of the late Roman wall. 
Despite its decline, Athens was still a small but secure center for the civil, military, and ecclesiastical administration. The walls, and especially those of the Acropolis, made the city an impregnable fortress that could provide safe refuge for its own population and that of the surrounding rural area in the hour of need. There also seems to have been a local aristocracy, as suggested by the fact that in the late eighth and early ninth centuries two residents of Athens, Irene and her niece Theophano, ascended the throne of Byzantium. 
A period of general reconstruction and administrative reorganization began for Byzantium after the middle of the ninth century and culminated in the centuries that followed. The population began to grow at a regular rate once more, the circulation of money increased, and favorable conditions were created for the revitalization of the urban centers. Against this background, Athens started to recover. Administratively, the city was part of the theme of Hellas formed in the late seventh century with its capital in Thebes. However, it seems that during the first half of the ninth century Athens may have been the seat of the theme. Furthermore, the bishopric of Athens was elevated to the rank of archbishopric before the middle of the ninth century and to that of metropolitan bishopric late in the tenth century. At the same time, the “renowned church of the Mother of God”, housed in the Parthenon, had begun to attract pilgrims from all over the empire, while in 1018 Basil II dedicated his victory over the Bulgars to the Virgin of Athens.
In the eleventh and twelfth centuries, numerous churches were built in the area between the late Roman wall and the outermost fortifications—a sure indication that the city was prospering. They were founded, of course, by members of the local aristocracy of landowners and state officials, which was very powerful in society and the economy at that time. These churches, some of which can still be seen today (the Holy Apostles in the Agora, Kapnikarea, Sts. Theodore, Hagioi Asomatoi, Gorgoepikoos, and others) are of the cross-in-square type; they are small in size, with richly decorated facades and harmoniously articulated masses crowned by an elegant dome. The Greek-cross octagon type with a large dome is represented by Sotera Lykodemou, then the katholikon of a monastery on the outskirts of the town. There are also links between the aristocracy and the monasteries founded around the city in the eleventh and twelfth centuries. The most important of these is Daphni, the classicizing elegance of whose mosaics reveals close links to the art of Constantinople.
In 1204 the lower city was destroyed by Leo Sgouros, ruler of Nauplion, and at the end of the same year the city was handed over to the Franks. Over the next 250 years, it was ruled, successively, by the French dukes de la Roche and de Brienne (1204–1311), the Catalans (1311–87), and the Acciajuoli family of Florence (1387– 1456). After the relative peace of government by the French princes came the brutality of the Catalans, when the Athenians declined into “the ultimate slavery” and “exchanged their former felicity for boorishness”. Under the Florentine dukes, social and economic conditions improved, and the seat of the duchy moved from Thebes to Athens.
Among the first concerns of the French dukes was to strengthen the defenses of the Acropolis—of the Castel de Setines, as Athens was now called. In the first half of the thirteenth century, a fortified precinct was constructed at the foot of the Acropolis (known as Rizokastro) and toward the middle of the century the fortifications of the Acropolis were improved and the Sacred Rock became a medieval citadel. A strong wall (proteichisma) was built across its main entrance and a high watchtower now rose on the south wing of the Propylaia. Much important building work was also done under the Florentine dukes. Duke Nerio I (1387–95) converted the Propylaia into a Florentine palace, embellished the Parthenon, and repaired churches in the town. Throughout the period of Frankish rule, the city was confined within the late Roman wall, and the area beyond that fortification became a wasteland. In 1456, when the last Florentine duke surrendered Athens to the Turks, a new period in the long history of the city began.