The Rosetta Stone is a famous ancient artifact that has helped scholars unlock the secrets of ancient languages. Discovered in 1799, the stone is a granodiorite stele inscribed with three versions of a decree issued in 196 BC by the Egyptian
From Wikipedia
The Rosetta Stone is a stele of granodiorite inscribed with three versions of a decree issued in 196 BC during the Ptolemaic dynasty of Egypt, on behalf of King Ptolemy V Epiphanes. The top and middle texts are in Ancient Egyptian using hieroglyphic and Demotic scripts, respectively, while the bottom is in Ancient Greek. The decree has only minor differences across the three versions, making the Rosetta Stone key to deciphering the Egyptian scripts.