Stone Town is located along a natural harbour and the first Europeans to set foot on the island of Zanzibar were the Portuguese. The Portuguese ruled the island for over 2 centuries and began constructing Stone Town's first stone structure, the Old Fort. However, towards the end of the 17th century the Sultanate of Oman took over the island and completed the fort to prevent future attacks. The first stone houses in Stone Town probably began to be built in the 1830s, gradually replacing an earlier fishing village around the Old Fort. At the time the Sultanate of Oman controlled the Zanzibar Archipelago, Mombasa and the Swahili coast.