Chapter 244: Tears of a Strong Man.
He took Alexander and Dobby out the forest in which a giant whale-shaped tree was. He led the way to the inside of it.
"These pathways have been like this for hundreds of years. This forest is also protected by the guardians."
After a while, they came to a big chamber on whose center, a big red cube was situated.
Alexander couldn't recognize the language written on it. ~Ghost, scan it and decipher it.~
Ghost immediately replied to him, "Sir, there is not enough data to decode this language. This language doesn't match any existing language in the world."
Alexander walked to the cube and used his speaking power on it. It told him what the cube was and that there were four of them.
Duke Hitsugisukan started to tell Alexander about it as well, "These stones are called Poneglyphs. Studying them is banned by the world government. From that Kozuki clan seal, you can see that it has a relationship with Wano."
Alexander interrupted, "Let me guess, they made this 800 years ago?"
Duke Hitsugisukan nodded. "Yes, these red ones are called Road Poneglyphs. There are four of them and each points to a different location. Once you join all the four points with an imaginary line, where it bisects is where the last Island in Grand Line is. There are two more types of Poneglyphs.