Although the Pisan cross itself dates to 1017, the oldest surviving representation is a carving on the city walls, built in 1156 by counsellor Cocco Griffi. The city flag, red with the white cross on it, was officially recognized by Pope Callixtus II. The previous flag of Pisa was a plain field of vermillion, derived from the flag of Imperial Rome.
Today, the cross remains a symbol of the city. A red shield with the cross on it is the official arms of the Comune of Pisa. It also appears in the lower-right quarter of the ensign and coat-of-arms of the Italian Navy, which combines it with the emblems of the other medieval Maritime Republics: Venice, Genoa and Amalfi.
