NY: Facts on File, 1994.
Reference librarians are very familiar with this publisher, which has put out a long, long string of useful ready-reference volumes on an impressive array of topics. Because of my long-term interest in classical history, this one has a prominent spot on my own shelf, and it’s been heavily thumbed over the past fifteen years.
Basically, if there’s a person, or a place, or a literary work, or a reference to something from everyday life, anywhere in the 1,200 years of Rome’s royal, republican, and imperial history, you have a good chance of finding it explained here.
There are nine thematic chapters, ranging from a general outline of Rome’s history, its geography, and its military affairs, to travel and economics, literature and religion, and the minutiae of life as a Roman. Under those headings, you’ll find (for instance) the organization of the standard Roman legion and how it changed over time (including ranks, weapons and armor, and fortress plans), the types of municipalities established and sponsored by the central government (the Romans were very big on planning as opposed to allowing settlements to grow organically), the fostering of the brick and tile industries, literacy and education at the various levels of society, the change in official attitudes toward Christianity and other intrusive and competing religious movements (religion was a matter of state control in Rome, not personal beliefs), and the function of slavery (which was not at all race-based). There also are a number of quick-reference lists, covering emperors and literary figures and other prominent persons, deities, provinces, abbreviations found in monumental inscriptions, weights and measures, and other complex subjects. More than a hundred illustrations elucidate the volume. The bibliography runs only about a dozen pages, but there are other sources for that — including a couple from this same publisher.
If you’re a student of ancient Rome, or a fan of historical fiction with a classical setting, or just a junky of miscellaneous information, I can strongly recommend this volume. And you might take a look at the publisher’s catalog, too.