Boyen fortress, Gižycko, Masuria, Poland 2014 Another video Boyen fortress, part 2 youtu.be/YeaD-4GqtKw Boyen Fortress (Polish: Twierdza Boyen) is a former Prussian fortress located in the western part of Giżycko, in Warmian-Masurian Voivodeship, northeastern Poland. It is situated on a narrow isthmus between two large lakes of the Masurian Lake District, Kisajno and Niegocin. The Boyen Fortress was built between 1844-1856 (or 1843-1855 according to some sources) by order of King Frederick William IV, with a workforce of about 3,000 soldiers