Ancient Rome wouldn't be all that different from a modern superpower if they had mastered electricity or figured out how to make concrete,
I know this is completely off topic, and I apologize, but this just bugged me. Romans actually did invent concrete (that's how the Pantheon was built), but the knowledge was lost due to the barbarian invasions.
And to give this a more "ancient alienish" spin, I'll just say that this is a good example of how we underestimate the abilities of ancient civilizations. There's no need to attribute alien assistance to any of their achievements. Then again, that doesn't mean they haven't visited. But if they had, I'd be more inclined to believe we were for them more like an ants nest, or some monkeys or something, i.e. of no particular interest (given the age of the universe, and the relatively small time it would take for a civilization to develop, the chances of a neighboring visiting civilization being on the roughly same level as us are minuscule... then again, maybe not... maybe a relatively equally developed civilization from a somewhat more distant part of the galaxy developed FTL and bumped into us, but I'd wager they'd too just leave us alone... unless a couple of them crash-landed and the locals helped them, and they taught them stuff in return, but as I said that's more SF, and not science or history, it's not probable nor is there any evidence whatsoever.).