Algiers ( al-JEERZ; Arabic: الجزائر, romanized: al-Jazāʾir) is the administrative, political and economic capital and largest city of Algeria as well as the capital of the Algiers Province. The city's population at the 2008 census was 2,988,145 and in 2020 was estimated to be around 4,500,000. Located in the north-central part of the country, it extends along the shores of the Bay of Algiers in the heart of the Maghreb region making it classified among the biggest cities in North Africa, the Arab world and the Mediterranean Sea, making it a major center of culture, arts, gastronomy and trade.

The city contains the largest infrastructure facilities in the country; railway and highway connections with neighbouring cities and international links via the Houari Boumediene Airport and Algiers Ferry Terminal. Algiers possesses notable mass transit options, that includes the Algiers Metro, the city's subway system that recorded about 46 million passengers in 2023, alongside the Algiers tramway and several Gondola lift lines helping with the difference in elevation, in addition to many bus lines connecting the suburbs and major population centers.

Algiers houses many museums, art galleries and cultural centers, the most notable of which are Algiers Opera House, the Algerian National Theater Mahieddine Bachtarzi, Bardo National Museum (Algiers), the National Museum of Fine Arts of Algiers, The National Museum of Antiquities and Islamic Art; the "National Museum of Miniatures, Illumination and Calligraphy" located inside of Dar Mustapha Pacha; "Palais des Rais"; Algerian Admiralty Museum; the Central Military Museum adjacent to Maqam Echahid (Martyrs Memorial), a breathtaking monument that sits above the Martyrs National Museum. Other landmarks include Djamaa el Djazaïr, the 3rd biggest mosque in the world; Botanical Garden Hamma; Culture Palace Moufdi Zakaria; Grande Poste d'Alger, located adjacent to Kilometre zero; Ketchaoua Mosque; Notre-Dame d'Afrique; Emir Abdelkader Square as well as Martyr's Square. The city also contains a UNESCO World Heritage Site, the Casbah or citadel, that is a prominent example of Casbah and Medina.

This metropolis has hosted many sports events such as the 1975 Mediterranean Games, the 1990 African Cup of Nations alongside Annaba, the 1978 All-Africa Games and 2007 All-Africa Games, the 2018 African Youth Games, the 2022–23 CAF Confederation Cup, the 2023 Arab Games with 4 other cities; the 2022 African Nations Championship with 3 other cities. Sonatrach Petroleum Corporation and Air Algérie are headquartered in the city.