Best Art History sites
Heilbrunn Timeline of Art History (The Metropolitan Museum of Art)
For example, see chronology for '1900 until the present' and select geographical areas to see art examples, timeline and background information for art in that period/place.
Google Arts and Culture Artists, mediums, art movements, and more.
Arts and facts (podcasts)
Art History resources (later C20)
The Art History Archive including links to art and artists from various countries and cultures
Best Art History Websites (EdTechTeacher)
Arts Online Art History includes art periods in chronological order, Art styles and movements, and more.