This is "The Shabako Stone," a large, rectangular slab of conglomerate stone that once served as a stela and was later reused as a millstone. This reuse explains the damage you can see across much of the surface, especially where the hieroglyphs were worn away by the grinding process.
At the top, the stone features two rows of hieroglyphs that mention Pharaoh Shabako and suggest he took great care to preserve an ancient text. Beneath these are sixty vertical columns of text, recording the "Memphite Theology"—an ancient creation myth. In this story, the god Ptah is credited with creating all things through speech, an idea that helped reinforce the religious and political standing of Memphis.
Made during the 25th Dynasty, around 710 BC, the stone comes from Memphis, a key city of ancient Egypt. While the text may not be as old as it claims to be, it reflects the cultural and religious values of the time and was likely used as a tool to strengthen the Nubian Pharaoh’s authority in Egypt.
The Shabako Stone is on display in Room 4 at the British Museum on Great Russell Street, Bloomsbury, London — free to enter. Choose British Museum on audioguide.london and take a photo of it to hear this free audio guide in six languages — no app download needed.
New, in beta. British Museum support has just launched and is still improving: over 1,000 objects so far, with more added all the time.