Poneglyphs are the stones on which the events of the Void Century, and also, the location of Ancient Weapons are inscribed. These stones are also extremely strong and cannot be destroyed by anything.
There are only 5 people so far who know how to read them. So, today I have made a list of all 5 people who know how read Poneglyphs.
5. Nico Robin
Nico Robin is a member of the Strawhat Pirates, and is also their archeologist. She has a bounty 130,000,000 berries.
She was from Ohara, and knows how to read and write Poneglyph. Robin mastered this language all by herself.