 The flag was officially adopted on 5 February 1975 although it was already in use before this date, seen for example on the cover of the day programme of the 1928 Summer Olympics held in Amsterdam.Before its official adoption there was also an unofficial use of a flag with the city's coat of arms in the middle of a red-white-black horizontal tricolor.Such a design was already in use in the 17th century, but in Amsterdam history, other designs in the colors red, black and white were also used.