Kolkata, also known as Calcutta, is the capital and largest city of the Indian state of West Bengal. It lies on the eastern bank of the Hooghly River, 80 km (50 mi) west of the border with Bangladesh. It is the primary financial and commercial centre of eastern India and one of the gateways to northeastern India. Kolkata is the seventh most populous city in India with an estimated city proper population of 4.5 million while its metropolitan region Kolkata Metropolitan Area is the third most populous metropolitan region of India with a metro population of over 15 million. Kolkata is regarded by many sources as the cultural capital of India and a historically and culturally significant city in the historic region of Bengal.