The Torre del Oro (Spanish for "Gold Tower") is a dodecagonal military watchtower built in Seville, Spain by the Berbers during the Almohad dynasty in order to control access to Seville via the Guadalquivir river.
Constructed in the first third of the 13th century, the tower served as a prison during the Middle Ages and as a secure enclosure for the protection of precious metals periodically brought by the fleet of the Indies, another possible origin for the tower's name.
The tower is divided into three levels, with the third and upermost being circular in shape and added in 1760. This tower has a lesser known half sister: La Torre de la Plata, an octagonal tower.
It is one of two anchor points for a large chain that would have been able to block the river.The other anchor-point has since been demolished or disappeared, possibly from collapsing during the 1755 Lisbon Earthquake. The chain was used in the city's defense against the Castilian fleet under Ramón de Bonifaz in 1248 during the Reconquista.
The tower has a significant meaning to the citizens of Seville: At one point in the last two centuries the tower came under threat when the adjacent road needed widening, but faced by strong opposition from the locals the demolition idea was dropped. In 1868 it was put up for sale as scrap, but this too was vehemently rejected by the city's inhabitants.
Today the tower, having been restored, is a naval museum, containing engravings, letters, models, instruments, and historic documents. The museum outlines the naval history of Seville and the importance of its river.