ROSETTA STONE
The Rosetta Stone was the key to understand the Egyptian hieroglyphs.
It's a granodiorite stele built in 196 BC that contains a text in three different spellings: Ancient Egyptian hieroglyphs, Demotic, Ancient Greek.
It was discovered near the town of Rashid (Rosetta) in 1799 by Pierre-François Bouchard, a soldier of the Napoleonic army.
Jean-François Champollion, studying the Rosetta Stone, found the solution to decode the writing system of ancient Egypt.