"Porto is the second-largest city in Portugal, after Lisbon, and the name “Porto” itself influenced the name of the country “Portugal”.
Established by the Celts on the mouth of the Douro River, it was occupied by the Romans during the fourth century, transforming it into an influential commercial port and renaming it “Portus Cale”. In 456, it was invaded by Theodoric II, King of the Visigoths, who remained in their power until 716, when it fell under the Moorish Muslim invasion."