The flag of the Brussels-Capital Region of Belgium consists of a stylized yellow, grey and white iris on a blue background.

The plant used to surround the city walls and, according to legend, gave a key victory to the Dukes of Brabant: knowing the plant could only grow in shallow water, the Duke's troops could gallop through the flooded plains by keeping to the iris covered areas.

This included Charles of France, who set up a fortified camp in the area, in the Duchy of Lower Lotharingia, and chose the site as the capital.

The blue and yellow colours are those of the European Union, of which Brussels is the de facto capital city.

Opposition members complained that it is disrespectful and inappropriate to change a flag to suit the latest fashion in graphic design.