RASTENBURG, räs'ten-bōōrK. A town in the Province of East Prussia, Prussia, on the River Guber, 64 miles southeast of Königsberg by rail (Map: Germany, J 1). It has a royal gymnasium and a sanatorium for epileptics. Among the industrial establishments are iron and brass foundries, sugar factory, flouring mills, etc. Population, in 1900, 11,144.