ALTENBURG, a town in Germany, capital of the duchy of Saxe-Altenburg, situated near the river Pleisse, about 24 miles south of Leipsic. The town, from its hilly position, is irregularly built; but many of its streets are wide, and contain a number of large and beautiful buildings. Its ancient castle is picturesquely situated on a lofty rock, and is memorable as the place from which, in 1455, Kunz von Kaufungen carried off the young princes Albert and Ernest, the founders of the present royal and ducal families of Saxony. Altenburg is the seat of the higher courts of the duchy, and possesses a cathedral and several churches, a gymnasium, a library, a gallery of pictures and a school of art, several elementary schools, an infirmary, and various learned societies. There is considerable traffic in grain and cattle brought from the surrounding district; twice a year there are large horse fairs; and the book trade is extensive. Cigars, woollen goods, gloves, hats, and porcelain are among the chief manufactures. Population (1871), 19,966.