A detail from three scripts on the Decree of Canopus.

This 2,200-year-old slab bears the world's first mention of leap year

Evidence dating back to 238 B.C. shows that ancient Egyptians recognized the need for a leap year to correct the slow drift of the seasons.

A detail of a 3rd-century B.C. copy of the Canopus Decree written in Egyptian hieroglyphs and Demotic script, with an ancient Greek translation beneath. It provides the world's first record of a leap year.
Photograph by G. Dagli Orti, NPL - DeA Picture Library/ Bridgeman Images