Ghana, officially the Republic of Ghana, is a country in West Africa. It lies adjacent to the Gulf of Guinea and the Atlantic Ocean to the south, sharing a border with Ivory Coast in the west, Burkina Faso in the north, and Togo in the east. Ghana covers an area of 239,567 km2 (92,497 sq mi), spanning diverse ecologies, from coastal savannas to tropical rainforests. With nearly 35 million inhabitants, Ghana is the second-most populous country in West Africa. The capital and largest city is Accra; other significant cities include Kumasi, Tamale, and Sekondi-Takoradi. In 1957 Ghana became the first colony in Sub-Saharan Africa to achieve sovereignty, under the leadership of Kwame Nkrumah.