Mommensen's History of Rome
Excellent. I own and read Gibbon's (Pub. 1896) and Ferro's (Pub. 1923) Decline and Fall of the Roman Empire. A great read and collectible for Classical Historians. Mommsen's is a heavy read as Gibbon and Ferro but adds another perspective. Some of the information is outdated, due to more recent updated historical data. These volumes are still most valuable for he as well as Gibbon's are frequently referenced. It is evident that some Mommsen opinions are reflective of his time. This is a must for those interested in the period. I strongly recommend T. Hodkin's is "Italy and Her Invaders" (7 Vol). These volumes cover the effects, influence of the Visigoths, Ostrogaths, Lombards and Franks from the 14 AD to the Middle Ages. The contained history granulates these people in more depth than Gibbon, Ferra and Mommsen.