The Torre del Oro was built by the Moors in 1220 as part of Seville`s defences. By attaching a chain from the tower to another on the opposite bank, enemy ships could be prevented from sailing up the river. It is thought the tower`s name was derived from gold tiles that once covered the walls. The tower has been used for many purposes, including a chapel and a prison. Nowadays, the building houses a small maritime museum.