Roma Sub Rosa (the Gordianus series)

Steven Saylor's detective series set in Rome started out with one lovely distinguishing feature; the mysteries fictional 'detective' Gordianus investigated were real criminal cases, usually taken from Cicero's speeches. Saylor would offer an alternative solution to that presented by history, Gordianus delving into the secrets imagined to lie beneath the case. As the series has gone on, Saylor has invented more and more of the central mysteries himself, but the focus on historical events, now largely political and military events, remains.

2. The House of the Vestals
5. Catilina's Riddle
8. Rubicon
9. Last Seen in Massilia