The following chapter of our guide to Assassin's Creed Odyssey contains a list of all Ainigmata Ostraka available in the Makedonia region. Makedonia lies in the northern part of the map, bordering with Malis.
Location of the Ainigmata Ostraka: Leader's house in Makedonia. The item can be found on the ground floor, on the right side of the building.
Solving the puzzle: Lake located in the western part of Makedonia. On the shore, search in the plants.