Founded by the Phoenicians as the trading port of «Icosium», the city was rebuilt in the 10th century CE under the name «al-Jaza'ir» — «the Islands» — after the small islets that once lay off its coast, later joined to the mainland by harbour works.

Under Ottoman rule Algiers became a major naval base for the Barbary corsairs. Today the Casbah, a UNESCO World Heritage Site, preserves a maze of narrow alleys and tightly packed white houses cascading down the hillside toward the Mediterranean.