Until 1945: Prostken, Kreis Lyck, Regierung Allenstein, Ostpreussen [German]
(Prostki, County of Ełk, State District of Olsztyn, East Prussia [Polish]).

Prostki was founded in 1482. Its rapid development occurred mainly thanks to its location at the meeting point of borders of Prussia, Lithuania and Masovia. It is famous for the oldest border post in Central-Eastern Europe, dating back to 1545, which still stands today, and for the battle of the Prussian-Brandenburg and Swedish armies against the Tatars in 1656 (the battle was described by Sienkiewicz in “Potop”). Today it is a large village with small-town architecture centered around the elongated market square. In 1939 the population of Prostki numbered 2302 residents, while today 2541 people live there.