“Located on two islands close to each other just off the Tanzanian coast about 300km south of Dar es Salaam are the remains of two port cites, Kilwa Kisiwani and Songo Mnara. The larger, Kilwa Kisiwani, was occupied from the 9th to the 19th century and reached its peak of prosperity in the13th and 14th centuries. In 1331-1332, the great traveler, Ibn Battouta made a stop here and described Kilwa as one of the most beautiful cities of the world.
Kilwa Kisiwani and Songo Mnara were Swahili trading cities and their prosperity was based on control of Indian Ocean trade with Arabia, India and China, particularly between the 13th and 16th centuries, when gold and ivory from the hinterland was traded for silver, carnelians, perfumes, Persian faience and Chinese porcelain. Kilwa Kisiwani minted its own currency in the 11th to 14th centuries. In the 16th century, the Portuguese established a fort on Kilwa Kisiwani and the decline of the two islands began.
The remains of Kilwa Kisiwani cover much of the island with many parts of the city still unexcavated. The substantial standing ruins, built of coral and lime mortar, include the Great Mosque constructed in the 11th century and considerably enlarged in the 13th century, and roofed entirely with domes and vaults, some decorated with embedded Chinese porcelain; the palace Husuni Kubwa built between c1310 and 1333 with its large octagonal bathing pool; Husuni Ndogo, numerous mosques, the Gereza (prison) constructed on the ruins of the Portuguese fort and an entire urban complex with houses, public squares, burial grounds, etc.
The ruins of Songo Mnara, at the northern end of the island, consist of the remains of five mosques, a palace complex, and some thirty-three domestic dwellings constructed of coral stones and wood within enclosing walls.
The islands of Kilwa Kisiwani and Songo Mnara bear exceptional testimony to the expansion of Swahili coastal culture, the lslamisation of East Africa and the extraordinarily extensive and prosperous Indian Ocean trade from the medieval period up to the modern era.” UNESCO List of World Heritage