ALTENA, OR ALTONA, a sea-port town of Germany, in the duchy of Holstein in Lower Saxony. It is a modern town, built by the king of Denmark, and was burnt by the Swedes in 1712; but has since been beautifully rebuilt. The merchandise brought from Asia by the Danish East India Company is sold here. E. Long. 10. 0. N. Lat. 53. 51.