Kętrzyn is a town in northeastern Poland with 27,478 inhabitants. It is the capital of Kętrzyn County in the Warmian–Masurian Voivodeship. Th…Kętrzyn is a town in northeastern Poland with 27,478 inhabitants. It is the capital of Kętrzyn County in the Warmian–Masurian Voivodeship. The town is known for the surrounding Masurian Lakeland and numerous monuments of historical value such as the Wolf's Lair in nearby Gierłoż, which was Adolf Hitler's primary headquarters in Eastern Europe over the course of Nazi Germany's military campaign on the Eastern Front during World War II. The town is also known for its 14th century Teutonic Kętrzyn Castle.