Without Rome, zorostrianism would not only dominate Eastern europe, but would be the dominant religion in the world (note... not the ONLY one, but the DOMINANT, just like cristianity today), Road system would be much less developed, western architecture would have more arabic and hellen influence than latin (like today's southern france and mediteraneen states) Northen france would be totally diffent than southern, probably keeping much influence from celtic past. there would be MUCH more red-haired people in England and france, not having entered in contact (not is too big a word, but let's say much less) with the Latin gene. Americas would have been discovered, though later, as mentality and ideology wouldn't have been the same. but evolution is a race wich cannot be stopped, so at somepoint, european woulld have wondered still what lay behond that ocean.