Mumbai, a cosmopolitan metropolis, earlier known as Bombay, is the largest city in India and the capital of Maharashtra state. Mumbai was originally a conglomeration of seven islands on the Konkan coastline which over time were joined to form the island city of Bombay. The island was in turn joined with the neighbouring island of Salsette to form Greater Bombay. The city has an estimated metropolitan population of 21 million (2005), making it one of the world's most populous cities. The city is also famous as the heart of the Hindi-language Bollywood film industry.