This Ancient/Classical History site has a great deal of information on Roman history. [See: Why Does Rome Dominate Ancient/Classical History?.] Most of it is introductory in nature, and much of it very short. The material also branches off into more specialized topics of interest to me that were developed while reading articles and books on ancient Rome or Roman mysteries. These (possibly esoteric) topics are still intended to be introductions and many pages have references you can use as a starting point for further research. In addition to articles, there are list-format pages, including a list of about 60 terms to know about ancient Rome, timelines, names and dates of the Roman emperors, as well as pages that are annotated illustrations.