Osjorsk

Ozyorsk (Russian: Озёрск), known prior to 1938 by its German name Darkehmen (Lithuanian: Darkiemis; Polish: Darkiejmy), and from 1938 to 1946 as Angerapp, is a town and the administrative center of Ozyorsky District in Kaliningrad Oblast, Russia, located on the Angrapa River near the border with the Polish Warmian-Masurian Voivodeship, 120 kilometers (75 mi) southeast of Kaliningrad, the administrative center of the oblast. Population: 4,740 (2010 Census); 5,801 (2002 Census); 6,219 (1989 Census).
It was founded in 1724.
Before 1945 the town was part of Germany (East Prussia). After World War II and the subsequent border shift, the region was placed under Soviet administration and ethnically cleansed according to the post-war Potsdam Agreement, the native German populace was expelled.
Administrative and municipal status
Within the framework of administrative divisions, Ozyorsk serves as the administrative center of Ozyorsky District. As an administrative division, it is, together with one rural locality (the settlement of Ushakovo), incorporated within Ozyorsky District as the town of district significance of Ozyorsk.[1]
Within the framework of municipal divisions, since June 11, 2014, the territories of the town of district significance of Ozyorsk and of three rural okrugs of Ozyorsky District are incorporated as Ozyorsky Urban Okrug.[2] Before that, the town of district significance was incorporated within Ozyorsky Municipal District as Ozyorskoye Urban Settlement

Source Wikipedia

https://en.wikipedia.org/wiki/Ozyorsk,_Kaliningrad_Oblast

Important dates and facts:
Area: 12 km²
Population: 4740
Population density: 395 people per sq km