Utrecht, the smallest province in the centre of the Netherlands was founded as a bishopric in 722, with the mission to convert the heathen Frisians. It remained a bishopric for many centuries, a fact reflected in the design of the flag. The colours are based on the arms of the city of Utrecht (a shield, diagonally divided white and red). In the canton is the arms of the Archdiocese (Sticht) of Utrecht (a white cross on a red shield). The flag was officially adopted on 15 January 1952.