World-ology is a site for interactive maps, timelines, and articles of world history. The interactive maps are especially interesting as they chart a region, period, or event in history along a specific timeline. As you change the dates on the timeline, the maps change correspondingly. Naturally, I find the Middle Ages map the most useful for my focus of study. As you highlight and change time frames, the boundaries of the kingdoms shift, and hovering over the various kingdoms will show you summary details of that kingdom for a certain period in time.