Who assembled as library of greek and roman manuscripts preserving the works of cierco homer and virgil?

Answer 1

Michelangelo!
It was Charlemagne. He did not actually assemble a library. He commissioned monks and abbots to copy Roman manuscripts. These copies were preserved in monasteries and abbeys around Europe. They were forgotten for centuries. With the rebirth in interest in the Romans in the run up to and during the Renaissance Italian scholars scoured the monasteries and abbeys around Europe in search of these manuscripts. Without Charlemagne, we would have lost most of what we know about the Romans.