What is the setting of Claudius the God and His Wife Messalina by Robert Graves?

The novel's setting is a lightly fictionalized Roman Civilization. Often praised as historically accurate, the novel deviates from established historical interpretations only in a few minor points and usually only to provide tone or detail when such details are not known to historians. The novel's time period focuses on the initial decades of the life of Claudius, the protagonist, and spans from 10 AD through 41 AD. In popular terms, the novel's focus includes the latter period of Augustus' reign and the entirety of the reigns of Tiberius and Caligula.