Roma Sub Rosa

Roma Sub Rosa is the title of the series of historical mystery novels by Steven Saylor set in ancient Rome and populated by noteworthy denizens thereof. The phrase "Roma Sub Rosa" means, in Latin, "Rome under the rose". If a matter was "sub rosa", "under the rose", it meant that such matter was confidential.
The detective is known as Gordianus the Finder, and he mixes with non-fictional citizens of the Republic including Sulla, Cicero, Marcus Crassus, Catilina, Catullus, Pompey, Julius Caesar, and Mark Antony.
Characters.
For an ancient Roman, Gordianus has an unconventional family: 
Titles.
While the books were written in a different order, they are listed below in chronological order: