My current science fiction novel-in-progress, Fates With Traitors Do Conspire, starts out with Julius Caesar's crossing of the Rubicon in 49 B.C.E. and centers around the events leading up to and including his assassination on the Ides of March, 44 B.C.E.
Talk about the proverbial needle in a haystack! As I did research for this book, wading through available information on Rome turned out to be a more formidable task than I ever imagined. So much information can be found covering the millennia or so from Rome's founding to its fall, that pulling out information pertaining specifically to the Late Roman Republic was quite difficult.
Issues like how the Romans cussed, whether grafitti existed (and what form did it take), whether Rome had a fire brigade during this time, what the sanitary facilites were like, what religious beliefs were prevalent, how the government worked, how they kept track of time, what they ate, how long it took them to travel from point A to point B, and so forth, needed to be answered so that my book would have the level of verisimilitude that readers expect in any book which resembles historical fiction.
On my Ancient Rome page, I make available some of the information and resources that I've gleaned from my research in hopes that those of you who are writing historical fiction set in this period have an easier time of it than I did. It's also here for those of you who are just plain curious about such things. Enjoy.