Some historians are concerned that this series is used as a textbook of roman history pointing out there are some critical errors in the interpretation of historical records and the author's biased view. Nanami Shiono, the author, admits herself that she is not a historian, so this book should be enjoyed as a fiction. Having said that, she wrote this epic based on a massive amount of historical literature including those written by ancient historians such as Livy's "History of Rome," Polybius’s "The Histories" and Plutarch's Parallel Lives. Even if biased, the author saves her readers time and effort to read those literature to get a glimpse into rise of the ancient Rome.
I am lucky that I haven't been to Italy yet. Without reading this series, my impression of all the great ruins would be just "Wow, parts of such an old civilization can still be seen after more than 2000 years." But if you know how the Roman Forum was built, the ruins must look totally different.