Insular and semi-autonomous, Zanzibar joined Tanganyika to establish the United Republic of Tanzania in 1964. It is an island in the Indian Ocean that is located 25–50 kilometres (16–31 miles) off the coast of Africa. It is made up of numerous small islands as well as Unguja (the main island, also known as Zanzibar) and Pemba Island, two large ones. On the island of Unguja, Zanzibar City serves as the nation’s capital. Stone Town, the city’s historic core, is a World Heritage Site.