When the master plan for Islamabad was drawn up in 1960, Islamabad and Rawalpindi, along with the adjoining areas, was to be integrated to form a large metropolitan areacalled Islamabad/Rawalpindi Metropolitan Area. The area would consist of the developing Islamabad, the old colonial cantonement city of Rawalpindi, and Margalla Hills National Park, including surrounding rural areas. However, Islamabad city is part of the Islamabad Capital Territory, while Rawalpindi is part of Rawalpindi District, which is part of province of Punjab .
Initially, it was proposed that the three areas would be connected by four major highways: Murree Highway, Islamabad Highway, Soan Highway, and Capital Highway. However, to date only two highways have been constructed: Kashmir Highway (the former Murree Highway) and Islamabad Highway. Plans of constructing Margalla Avenue are also underway. Islamabad is the hub all the governmental activities while Rawalpindi is the centre of all industrial, commercial, and military activities. The two cities are considered sister cities and are highly interdependent.