Since the beginning of the civilization, Rome has made great strides in the field of engineering. Romans constructed bridges across the Tiber River. They also made aqueducts to ensure Rome's supply of water. Romans created sewers and drainage systems to drain the Forum and keep the city healthy. These were all amazing feats at the time.
Another amazing feat is that Rome was the first place to construct roads. They then connected the Empire further by creating such pathways. These roadways were so well designed that they still are around today.
This all supports the arguement that Rome's greatest acheivement has been in the field of engineering.