In the 19th century, the Rosetta Stone helped scholars at long last crack the code of hieroglyphics, the ancient Egyptian writing system. French army engineers who were part of Napoleon Bonaparte’s Egypt campaign discovered the stone slab in 1799 while making repairs to a fort near the town of Rashid (Rosetta).

The artifact, which is made of granitoid, came into the possession of the British after they defeated the French in Egypt in 1801.

The stone features a decree issued in 196 B.C. by a group of Egyptian clergy and Egypt’s ruler, Ptolemy V, attesting to his generosity and devoutness. It originally was displayed in a temple, possibly near the ancient town of Sais, then centuries later moved to Rosetta and used in the construction of Fort Julien, where it was eventually uncovered by the French.

The decree on the stone is written in three ways: in hieroglyphics, which was used mainly by priests; in ancient Egyptian demotic, used for everyday purposes; and in ancient Greek. The use of hieroglyphics died out after the 4th century and the writing system became an enigma to scholars.

British scientist Thomas Young, who began studying the Rosetta Stone’s texts in 1814, made some initial progress in analyzing its hieroglyphic inscription. Young surmised that the cartouches—hieroglyphs enclosed in ovals—contained the phonetic spellings of royal names, including Ptolemy, who was referenced in the Greek inscription.

Ultimately, it was French linguist Jean-Francois Champollion who deciphered the Rosetta Stone and cracked the hieroglyphic code. Between 1822 and 1824, Champollion showed that hieroglyphics were a combination of phonetic and ideographic signs rather than just symbolic picture writing that didn’t also represent sounds of language, as earlier scholars had suspected. For his discoveries, Champollion is heralded as the founding father of Egyptology.

Today, the Rosetta Stone, which measures about 44 inches tall and 30 inches wide, is housed in the British Museum in London, where it’s been since 1802, except for a temporary re-location for safekeeping during World War I to an off-site, underground spot.