The Decree of Canopus is a trilingual inscription in three scripts, which dates from the Ptolemaic period of Ancient Egypt. It was written in three writing systems: Egyptian hieroglyphs, demotic, and Greek, on several ancient Egyptian memorial stones, or steles. The inscription is a record of a great assembly of priests held at Canopus, Egypt, in 238 BCE. Their decree honoured Pharaoh Ptolemy III Euergetes; Queen Berenice, his wife; and Princess Berenice.
In 1866, Karl Richard Lepsius discovered at Tanis the first copy of this Decree (this copy was originally known as the 'Şân Stele'). Another copy was found in 1881 by Gaston Maspero at Kom-el-Hisn in the western Nile Delta. Later on, some other fragmentary copies were found. In March 2004, while excavating at Bubastis, the German-Egyptian 'Tell Basta Project' archaeologists discovered yet another well preserved copy of the Decree.
This is the second earliest of the series of trilingual inscriptions of the "Rosetta Stone Series", also known as Ptolemaic Decrees. There are four such Decrees, the earliest is the Decree of Alexandria from 243 BCE, the third being the Decree of Memphis, for Ptolemy IV in 218 BCE, and the fourth, final decree, being the Memphis Decree Rosetta Stone, inscribed for Ptolemy V, in 196 BCE. Having a greater number of different hieroglyphs than the Rosetta Stone, the Canopus Stone has proved crucial in deciphering them.