Question

Why do historians consider the greatest achievement of the Byzantine Empire to be the preservation of Greek and Roman cultures?

Answer 1

I think it's because it was hard for them to build at the time because of the building technology.

Answer 2

The Byzantines ended up being the survivors after the collapse of the Roman Empire in the West. But it was also an extension of Greek of culture (its capital used to be a Greek city), especially when a later emperor, Heraclius, made Greek the official language of the state. At the same time, it also inherited Roman laws and traditions as it was the Eastern half of the Roman Empire.