Zanzibar is the semi-autonomous part of Tanzania in East Africa. It is composed of the Zanzibar Archipelago in the Indian Ocean, 25–50 kilometres 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.Portuguese invasion and control of the Swahili Coast in the late 16th century ended the golden age of the archipelago, although the Omani Arabs returned to power less than a century later. Today, many of the winding streets and high townhouses of old Stone Town remain unchanged and visitors can walk between the sultan’s palace, the House of Wonders, the Portuguese fort and gardens, the merchants’ houses, and the Turkish baths of the old city. Day-long spice tours to working plantations offer visitors the chance to observe the cultivation of cloves, vanilla, nutmeg, cinnamon, and other spices that have made the island famous. Zanzibar’s offers some of the best beaches in the world.