How did the Romans use the legacies of other civilizations?

They get their techniques from them.

Well the romans incorporated many aspects of the Greek civilization as seen in their buildings, painting, mythology, and even war tactics. but as with everything out with the old in with the new. the romans sort of "improved" Greek ideas. for example roman paintings featured much more real features such as wrinkles and pimples whereas the Greeks hid such impurities.