Byzantine cities were important centers of trade, culture, and religion during the Middle Ages. Some of the most important Byzantine cities included Constantinople, the capital of the empire and one of the largest and wealthiest cities in the world; Thessaloniki, a major port and commercial center in the northern Aegean; Nicaea, a city in northwestern Anatolia that was the site of two important ecumenical councils; and Antioch, a city in modern-day Turkey that was one of the earliest centers of Christianity. Other notable Byzantine cities included Athens, Ephesus, Edessa, Trebizond, and Mistra. Each of these cities played a significant role in the history and culture of the Byzantine Empire, and their remains continue to inspire and fascinate scholars and travelers today.

However, the cities essence experience structural changes during the long history of the Byzantine Empire. In the early Byzantine period, many cities retained their ancient Roman or Greek character, with grand public buildings, wide streets, and well-planned urban layouts. As the empire faced various external and internal challenges, such as invasions, political instability, and economic decline, the cities began to change while villages became the backbone of the Empire´s economy. By the medieval period, many Byzantine cities had become smaller and more fortified, with narrow, winding streets and closely-packed houses. The focus of urban life shifted from the public sphere to the private, as people sought security and community within their own neighborhoods and religious institutions.

Despite these changes, Byzantine cities remained important centers of trade, culture, and religion and their subsiting monuments greatly contribute to the understanding of Byzantine architecture, art and society.