In 1770 , Port-au-Prince replaced Cap-Français ( the modern Cap-Haïtien ) as capital of the colony of Saint-Domingue , and in 1804 , it became the capital of newly independent Haïti .
Port-au-Prince was built in 1749 and , in 1770 , it replaced Cap-Français ( the modern Cap-Haïtien ) as capital of the French colony of Saint-Domingue .