With this app you can walk, ride or drive through the Greek countryside and not only identify the ruins along the road but also read what the ancients themselves had to say about them.
ToposText maps more than 5,000 places connected with the ancient Greek world: ancient cities and shrines, medieval castles and towers, modern museums and excavation sites. Locations are primarily in Greece but also include major sites through out the Mediterranean.
Then the application goes on to link those places to the ancient authors who wrote about them in Greek or Latin with translations to English, creating a huge and detailed gazetteer. In effect you can select and read the passages in ancient literature that give a place its historical and cultural context.
You can find all of this and more on their web site: https://topostext.org/
I recommend you read the current reviews before installing the app on your phone.
Or to find most major sites see the Peloponnese map on my Nafplio site