Rome was so powerful in ancient times because of:
- very advance administration system (including e.g. efficient tax system)
- justice system (providing unity and stability)
- strong army (including people from conquered lands)
- dynamic society (providing Romanization of new territories)
- well developed trade
- excellent engineering skills (ability to build roads, aqueducts, harbors, war machines etc.)
- focus on education (high level of literacy in comparison to other lands)