The island of Kilwa Kisiwani is located in the south of Tanzania, a short boat ride from the mainland. It was once a thriving seaport; from the eleventh century the sultans of Kilwa grew rich from control of the gold trade. Gold was mined at Great Zimbabwe far off in the interior, and carried by caravan and then by boat to Fatimid Cairo, passing through Kilwa on its way north. Kilwa grew in the thirteenth and fourteenth centuries and is mentioned by several early chroniclers. The most significant standing ruins from this period are the Great Mosque and the Palace at Husuni Kubwa. The palace was unrivaled in East Africa for its architectural sophistication and splendor. Founded in the fourteenth century, the Great Mosque was, up until the sixteenth century, the largest mosque in sub-Saharan Africa. In 1498, the Portuguese arrived in East Africa and quickly asserted control over the region’s trade. They built a fort at the edge of the town, which was completed in 1505.