Dhaka, formerly spelled as Dacca, is the capital and largest city of Bangladesh. With an estimated population of 36.6 million, Dhaka is the second largest city by population in the world, and is widely considered to be the most densely populated built-up urban area in the world. Dhaka is an important cultural, economic, and scientific hub of Eastern South Asia. Dhaka ranks fourth in South Asia and 55th in the world in terms of GDP. Lying on the Ganges Delta, it is bounded by the Buriganga, Turag, Dhaleshwari and Shitalakshya rivers. It is also the largest Bengali-speaking city in the world.