Karachi  is the largest city of Pakistan and the capital of the province of Sindh, its largest city, as well as one of the largest and most populous metropolitan cities in the world. Karachi metro has an estimated population of over 23.5 million people as of 2013, and area of approximately 3,527 km2 (1,362 sq mi),[9][10] resulting in a density of more than 6,000 people per square kilometre (15,500 per square mile).