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. 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 key attributes conveying outstanding universal value are found on the islands of Kilwa Kisiwani and Songo Mnara.