4. Tunis: It is the capital and largest city of the North African country, Tunisia. Agriculture remains a major source of income. Olives and cereals are the principal crops grown, and olive oil and foodstuffs are processed. Manufactures include textiles and clothing, carpets, and cement and metal building structures. There are also chemical (superphosphate), metallurgical, machine, and electrical industries and railway workshops. There are several thermoelectric plants at Ḥalq al-Wādī, and Maqrīn has a lead smelter. Tourism is of particular economic importance. Al-ʿUwaynah International Airport and the International Airport of Tunis-Carthage are located northeast of the city.