Frauenburg, a town of Prussia, in the province of East Prussia, 41 m. S. W. of Konigs-berg, on the Frische Haff, and at the mouth of the Baude; pop. about 4,000. It is the seat of the Catholic bishop of Ermeland. The cathedral, which is on an elevation, has six towers, and with its surroundings constitutes a kind of fortress; it contains the tomb of Copernicus, who in 1543 died here.