"The town was the centre of trade on the East African coast between Asia and Africa before the colonization of the mainland in the late 19th century after which the focus moved to Mombasa and Dar es Salaam. The town also became a base for many european explorers, particularly the portuguese, and colonizers from the late 19th century. David Livingstone used Stone Town as his base for preparing for his final expedition in 1866.
The old town is built on a triangular peninsula of land on the western coast of the island. The oldest part of the town consists of a warren of narrow alleys to houses, shops, bazaars and mosques. Its swahili architecture incorporates elements of Arab, Persian, Indian, European and African styles. The Arab houses are particularly notable because they have large and ornately carved wooden doors and other unusual features such as enclosed wooden verandas.
Two large buildings dominate the main front of Stone Town. One is Beit-El-Ajaib or the House of Wonders, which was built by Sultan Seyyid Barghash as a grand palace for ceremonial purposes. The other is the Arab Fort which stands on the site of a former Portuguese settlement and was converted to a fort during the 18th Century.
Stone Town has been designated by Unesco as a World Heritage Site. However, this designation does not provide complete protection for the town's heritage. In 1997, "of the 1709 buildings in the Stone Town, about 75% were in a deteriorating condition."" - in: wikipedia