INSTERBURG, a town in the kingdom of Prussia, situated at the point where the Angerapp and Inster join to form the Pregel, 57 m. E. of Königsberg by the railway to Eydtkuhnen, and at the junction of lines to Memel and Allenstein. Pop. (1900) 27,787. It has four Evangelical churches, of which the town church is celebrated for its fine wood carvings, a Roman Catholic church, a synagogue, several schools and a park. Besides flax-spinning and iron-founding, Insterburg has manufactures of machinery, shoes, cement, leather and beer, along with a considerable trade in cereals, vegetables, flax, linseed and wood, while horse-breeding is extensively carried on in the neighbourhood. Close to the town lies the demesne of Georgenburg, with an old castle which formerly belonged to the Teutonic order. Insterburg, the “burg” on the Inster, was founded in the 14th century by the knights of the Teutonic order. Having passed to the margraves of Brandenburg, the village which had sprung up round the castle received civic privileges in 1583. During the next century it made rapid advances in prosperity, partly owing to the settlement in it of several Scottish trading families. In 1679 it was besieged by the Swedes; in 1690 it suffered severely from a fire; and in 1710–1711 from pestilence.
See Töws, Urkunden zur Geschichte des Hauptamts Insterburg (Inst., 1895–1897, 3 parts); and Kurze Chronik der Stadt Insterburg (Königsberg, 1883).