Historical Locations are a specific type of point of interest in Assassin's Creed Odyssey that serve as an educational database, providing real-world context for the people, places, and myths of Ancient Greece. These locations allow players to learn about the history behind the game's setting while they explore.
By default, icons for historical locations are hidden on the world map to avoid cluttering the interface with non-gameplay objectives. To see them, you must open your map and cycle through the filters until the filter specifically displays "Historical Locations." Once active, you can hover over any eye icon to read a short blurb about that specific site.