Kolkata is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly river, it is the principal commercial, cultural, and educational centre of East India, while the Port of Kolkata is India's oldest operating port as well as its sole major riverine port. As of 2011, the city had 4.5 million residents; the urban agglomeration, which comprises the city and its suburbs, was home to approximately 14.1 million, making it the third-most populous metropolitan area in India. As of 2008, its economic output as measured by gross domestic product ranked third among South Asian cities, behind Mumbai and Delhi. As a growing metropolitan city in a developing country, Kolkata confronts substantial urban pollution, traffic congestion, poverty, overpopulation, and other logistic and socioeconomic problems.
In the late 17th century, the three villages that predated Kolkata were ruled by the Nawab of Bengal under Mughal suzerainty. After the Nawab granted the East India Company a trading license in 1690, the area was developed by the Company into an increasingly fortified mercantile base. Nawab Siraj ud-Daulah occupied Kolkata in 1756, and the East India Company retook it in the following year and by 1772 assumed full sovereignty. Under East India Company and later under the British Raj, Kolkata served as the capital of India until 1911, when its perceived geographical disadvantages, combined with growing nationalism in Bengal, led to a shift of the capital to New Delhi. The city was a centre of the Indian independence movement; it remains a hotbed of contemporary state politics. Following Indian independence in 1947, Kolkata—which was once the centre of modern Indian education, science, culture, and politics—witnessed several decades of relative economic stagnation. Since the early 2000s, an economic rejuvenation has led to accelerated growth.