roma sub rosa
Saylor writes stories of the mean streets, of political intrigue, sex scandals, malfeasance, dishonest lawyers, corrupt judges, and rioting in the streets. His sleuth is a man of little family background named Gordianus the Finder.
Oh, yes--they are all set in ancient Rome, just before the Imperial Age, and most of the principal characters are historical figures. The political intrigues, scandals, and rioting are as reported by various classical authors, from Cicero (often on-stage in his own right) on down. Think of it as ancient Roman True Crime.
The books should definitely be read in order, as each builds on its predecessors, in terms of both Roman History and Gordianus' life. The House of the Vestals is a collection of short stories.
Those who like Gordianus might also enjoy' somewhat lighter-hearted tales of informer Marcus Didius Falco, set a century or so later in the days of Emperor Vespasian.