Which contribution of the Byzantine roman empire had the most lasting impact on western civilization

Justinian code

Explanation:

The Justinian code is the biggest contribution of the Byzantine Empire that managed to have a lasting impact on all of the Western societies. The impact can be seen in the law and legislation, as the Justinian code is actually the basis of all of the Western laws and legislation. Even though it has not been fully implemented, it has been what has given the directions. The reason for this is that the Justinian code was seen as the best one, the one that was the most just, and the one that was good for proper organization and control over the society.