Mumbai (previously known as Bombay until 1996) is a natural harbour on the west coast of India, and is the capital city of Maharashtra state. It is India's largest city, and one of the world's most populous cities. It is the financial capital of India and a global city. Many billionaires live there. The city is the second most-populous in the world. It has approximately 13 million people. Along with the neighbouring cities of Navi Mumbai and Thane, it forms the world's 4th largest urban agglomeration. They have around 19.1 million people.