), Kocaeli (capital: Izmit ) and Sakarya (capital: Adapazar? ). Provinces with the largest populations are Istanbul (+12.9 million), Ankara (+4.6 million), Izmir (+3.8 million), Bursa (+2.5 million) and Adana (+2.0 million). The biggest city and the pre-Republican capital Istanbul is the financial, economic and cultural heart of the country. [