Kilwa Kisiwani
An island located off the coast of East Africa in modern-day southern Tanzania, Kilwa flourished as an independent city-state from the 12th to 15th century CE as it had full control of the gold coming in from neighboring Zimbabwe Empire, making it very wealthy.
Kilwa boasted of fine stone buildings, a huge palace complex and wooden doors that demonstrated the advancement and sophistication in its architecture. Its many forts, mosques, and trading centers were vastly admired by Arab merchants and Portuguese traders. One of the most beautiful and well-constructed cities in the world, Kilwa was burnt down by Portuguese forces in 1505. In recent times, the Great Mosque and Palace at Husuni Kubwa are a few of the ruins that remain in somewhat good shape.