Byzantium

I'd like to spend a few words in favour of the roman empire.

In western europe, we grew up with the notion that the roman empire was ended when rome was taken.
Wrong, it went on. The empire absolutely lived with its imperial traditions long after.
In its new capital. A capital that was chosen much earlier than Roma was taken.
The capital of the emperor, head of the state and representative of Christ.

It was an empire that kept alive science, whose destruction by the turks led to the Renaissance in Italy, driven by the found-again science and philosphy that the greek speaking intellectuals from the roman empire brought with them.

An empire of christians next to muslims. Using arabs, before they were muslims, to fight the germanic tribes. Then using vikings to protect the emperor.

The world has always been a lot closer than we think. Only the last 2 centuries allowed governments to have such a strong grip on citizens and borders could really be closed off.