Mumbai formerly called as Bombay is the Maharashtra state capital and the largest city in India with an area if 4,355 km². Mumbai is also the wealthiest city in India, and contributes to more than 6% of the total Indian economy. Mumbai has headquarters of NSE, BSE, RBI, and many other important establishments. The port city is also the headquarter for giant conglomerates and companies like India Reliance Industries Limited, Tata Group, and Aditya Birla Group.
Kolkata is the capital city of West Bengal and grabs 2nd second spot in this list with an area of 1,851.41 sq.km. Situated on the banks of Hoogly River, Kolkata is one of the densely populated cities in India with a population exceeding 5 crores. Popularly known as City of Joy, Kolkata was once the capital of British India and has various educational institutes, govt organizations and research institutes. Kolkata houses many premier research institutes like Indian Association for the Cultivation of Science (IACS), Indian Institute of Chemical Biology (IICB), Indian Institute of Science Education and Research (IISER). ITC Limited, Coal India Limited, National Insurance Company, Exide Industries and Britannia Industries rank among the companies headquartered in the city.