Zanzibar is a semi-autonomous part of Tanzania in East Africa. It is composed of the Zanzibar Archipelago in the Indian Ocean, off the coast of the mainland, and consists of many small islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba. The capital is Zanzibar City, located on the island of Unguja. Its historic centre is Stone Town, which is a World Heritage Site.