Mumbai is the capital city of the Indian state of Maharashtra. It is the most populous city in India with an estimated city proper population of 12.4 million as of 2011. Along with the neighbouring regions of the Mumbai Metropolitan Region, it is the second most populous metropolitan area in India, with a population of 21.3 million as of 2016. Mumbai lies on the Konkan coast on the west coast of India and has a deep natural harbour. In 2008, Mumbai was named an alpha world city. It is also the wealthiest city in India, and has the highest number of millionaires and billionaires among all cities in India. Mumbai is home to three UNESCO World Heritage Sites: the Elephanta Caves, Chhatrapati Shivaji Maharaj Terminus, and the city's distinctive ensemble of Victorian and Art Deco buildings.