Greater Dhaka is the megalopolis including and surrounding the Bangladeshi capital city of Dhaka, which has grown into one of the world's largest megacities, and shows a very rapid rate of expansion. Dhaka not only grows because it is the capital and largest urban centre but also due to massive internal displacement from millions of people living in a perennially flood-prone river delta. This urban area now contains the 2nd most populated megacity in the world.