And if the Roman Empire had never disappeared? With "If" they put Paris in a bottle. Robert Silverberg he leads us through eleven chapters which are all dated chronological landmarks "ab urbe condita" (since the founding of Rome in 753 BC) in a parallel world that is essentially different from ours by some event changes the origin, but which radically change the direction of history: No development of the three monotheistic religions, disastrous attempts to conquer America ... Byzantium and Rome are waging a war without thank you, a decadent monarchy gave way to a bloody Terror, then to the Republic, a "Roman" language (Italian) develops from Latin. Technical progress is a bit slower. Excellent construction in which the author cleverly transplant imaginary elements from real situations to create a credible set. Clear and well-written novel that could delight fans of fictionalized ancient history (or not), at the end of which one can not but ask: "What if?"