Erratic boulders in Warmia and Mazury arrived from Scandinavia during the glaciation period. During the last thousand years, a significant part of the durable material, which is stone, was used to erect defensive, religious, residential and road buildings
Many stones fell in the 20th century. During World War II, stones were obtained on an industrial scale in Błaskowizna on Lake Hańcza. The aggregate produced from them was used to build bunkers in Wilcze Szaniec. In the past, the Prussians treated the largest stones as objects of worship or used as sacrificial altars. Such a Prussian sacrificial altar is the foundation of the altar in the Protestant church in Olsztyn. Currently, individual boulders are under conservation protection and are nature monuments.
