Madrid French Cerdagne ( France ) Largest city Font-Romeu-Odeillo-Via Demographics Demonym Iberian Population ~53 million Ethnic groups Andorran , Gibraltarian , Portuguese and Spanish ( Andalusian , Aragonese , Asturian , Basque , Cantabrian , Castilian , Catalan , Extremaduran , Galician , Leonese , Valencian , etc.) The Iberian Peninsula