Bell, Albert A. The Blood of Caesar. Set in ancient Rome, this mystery has Pliny the Younger and Tacitus investigating the missing memoir of Nero's mother, the death of a Jewish slave, and the possibility of a previously unknown descendant of Nero who might provide a rallying point for those who would challenge Emperor Domitian.
An interesting look at Rome and some of its well-known figures and some of its social and political intricacies, but the characters just didn't come off the page for me. Does include a chronological timeline and a list of terms and people at the back.
My favorite Roman mysteries are those of Lindsey Davis and the irrepressible Marcus Didius Falco. Lindsey Davis and Stephen Saylor (Gordianus the Finder) are perhaps the most familiar authors who use ancient Rome, but there are quite a few others as I discovered at The Detctive and the Toga. Here is a list of recently published Ancient Roman Mysteries.
Fiction. Historical mystery. 2008. 252 pages.