The city of Port-au-Prince is on the Gulf of Gonâve: 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 French colonial rule in 1749. The city's layout is similar to that of an amphitheater; 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 metropolitan area's population at around 3.7 million, nearly half of the country's national population. The city was catastrophically affected by a massive earthquake in 2010, with large numbers of structures damaged or destroyed. Haiti's government estimated the death toll to be 230,000.