As with most subjects, it's difficult to sort out what is "serious history" and what is chaff. Are the sources good? Is the "historian" respectable? Is there an ideological component, conscious or not? Luckily, someone (actually a super-someone or someone with helpers) has done a lot of the sorting for us, has organized the material, and has put it in one fairly simple (but really big) Internet site. Go to the Rome section of the Ancient History Sourcebook at http://www.fordham.edu/halsall/ancient/asbook3.html#Rome, and find more than anyone has the time to absorb on ancient Rome.
As noted, Rome is only one section of the Ancient History Sourcebook, and there are other Sourcebooks too. If your interests lie elsewhere, or if you finish everything listed for Rome, there is plenty more available on other times and places. In fact, the History Sourcebook Project, directed by the above mentioned super-person, Paul Halsall at Fordham University, pretty much covers everything historical that's available on the Internet about the whole world from the dawn of recorded history until today. You can find it all at http://www.fordham.edu/halsall/. The whole shebang is searchable.
Caution: history is addictive! Don't
let it take the place of experience! Read it on the Internet, but make
sure you also go to the real-world site!