Islamabad is the capital city of Pakistan. It is the country's ninth-most populous city with a population of 1,108,872 people and is federally a…Islamabad is the capital city of Pakistan. It is the country's ninth-most populous city with a population of 1,108,872 people and is federally administered by the Pakistani government as part of the Islamabad Capital Territory. Built as a planned city in the 1960s and established in 1967, it replaced Karachi as Pakistan's national capital.