Kolkata is the capital of the Indian state of West Bengal, located on the eastern bank of the Hooghly River, approximately 80 kilometres (50 mi) west of the border with Bangladesh. It is the prime business, commercial, and financial hub of eastern India and the main port of communication for the North-East Indian states, as well as having the third-largest urban economy of India. According to the 2011 Indian census, Kolkata is the seventh-most populous city in India, with a population of 4.5 million residents within the city limits, and a population of over 14.1 million residents in the Kolkata Metropolitan Area, making it the third-most populous metropolitan area in India. The Port of Kolkata is India's oldest operating port and its sole major riverine port. Kolkata is known as the "cultural capital of India" for the city's historical and architectural significance.