The Phoenicians founded the city of Oea in the 7th century BCE. Together with the Roman cities of Sabratha and Leptis Magna, it formed a region the Greeks called «Tripolis» — «three cities» — a name later inherited by Oea alone.

The Old City of Tripoli preserves the Red Castle (Assaraya al-Hamra), originally raised under Spanish rule and later developed by the Ottomans, now housing a museum with artefacts spanning Phoenician, Roman and Islamic eras.