 Alfonso VI of León and Castile entrusted the tenencia to Diego López I de Haro after the death of count García Ordóñez and the first of the lords of Biscay to attach the name of this town to his patronymic was Diego's son, Lope Díaz I de Haro.Heraldry and Vexillology

The shield of Haro is made in the center of a castle with battlements on gules, Mazon and doors and windows.On both sides of it, large lions rampant.