Constantinople, the capital city of the Byzantine Empire, was built on the site of the ancient Greek colony of Byzantium, on the triangular peninsula formed by the Golden Horn, the Bosporus and the Sea of Marmara. This was an excellent location that controlled trade routes linking the Aegean to the Black Sea. Emperor Constantine founded Constantinople in 330 AD as a city to rival Rome in splendour, wealth and power. The city grew fast, leading to problems of space and facilities, so Theodosius I extended it to the west by building new strong walls that protected Constantinople until the end of the Byzantine Empire.

The city was laid out after Rome. A main road, the Mese Odos, linked the palace to the Golden Gate. On this road was the Forum, a circular plaza with a statue of Constantine mounted on a column, surrounded by public buildings. Theodosius I and Arcadius later built more forums decorated with their own statues.

Following the Nika riots in the 6th century, Justinian adorned Constantinople with magnificent edifices, palaces, baths and public buildings. This time also saw the construction of Agia Sophia (the Holy Wisdom), the church which served as the seat of the Ecumenical Patriarchate throughout the Byzantine period.

During the 7th and 8th centuries Constantinople faced major problems that threw it into disarray: attacks by the Avars (a siege in 674) and Arabs (attacks in 674 and 717-718); natural disasters (a powerful, destructive earthquake in 740); and epidemics (plague in 747). Limited building activity resumed in the 8th and 9th century, mainly concentrated on strengthening the city's fortifications.

With the recovery of the Byzantine Empire from the 9th to the 11th century, Constantinople became the most populated city in Christendom; the majority of inhabitants were Greek-speaking, but many other ethnic groups lived alongside them, such as Jews, Armenians, Russians, Italians merchants, Arabs and mercenaries from Western Europe and Scandinavia.

Many public, private and church-owned buildings were erected at the time, with an emphasis on establishing charitable institutions such as hospitals, nursing homes, orphanages and schools. Higher education flourished, thanks to the care of the state and the emergence of important scholars. This renaissance lasted until the mid-11th century, when economic problems due to poor management set in, compounded by the adverse outcome of imperial operations beyond the borders.

The Crusaders left Constantinople entirely unscathed when first passing through, but in the Fourth Crusade of 1204 the Franks conquered and ransacked the city, slaughtering those inhabitants they did not take prisoner or drive out. In 1261 the city was retaken by Michael VIII Palaeologus, who rebuilt most of the monuments and the walls but proved unable to restore the city to its former splendour and glory. Enfeebled as it was, the empire was incapable of checking the advance of the Ottomans, and in 1453 Constantinople finally fell into their hands.

The fall signalled the end of the empire. Nevertheless, the Byzantine intellectual tradition remained significant, as many scholars settled in the Venetian dominions of Crete and the Peloponnese, as well as in European countries, conveying Greek learning to the West.