The city of Port-au-Prince faces the Gulf of Gonâve, at 18°32′N 72°20′W. The bay on which the city lies, which acts as a natural harbor, has sustained economic activity since the civilizations of the Arawaks. It was first incorporated under the colonial rule of the French, in 1749, and has been Haiti’s largest metropolis since then. The city’s layout is somewhat similar to that of an amphitheatre; commercial districts are near the water, while residential neighborhoods are located on the hills above. Its population is difficult to ascertain due to the rapid growth of slums in the hillsides above the city; however, recent estimates place the city’s population at between 2.5 and 3 million people.