Janowiec Kościelny  Janowiec Kościelny is a village in Nidzica County, Warmian-Masurian Voivodeship, in northern Poland. It is the seat of the gmina (administrative district) called Gmina Janowiec Kościelny. It lies approximately south-east of Nidzica and south of the regional capital Olsztyn. The village has a population of 360.