An e-mail from the MetMuseum today led me to its Heilbrunn Timeline of Art History, and the subsections Roman Republic and Roman Empire. Both pages have related timelines and links to Thematic Essays.
They are interactive in many ways, as the Fresco wall painting from the Villa of P. Fannius Synistor at Boscoreale shows.
ca. 40–30 b.c., Late Republican Roman, Pilaster
Image courtesy www.metmuseum.org, click on it for interactive page.