The Boyen fortress is undoubtedly a unique object and the most interesting monument in Giżycko and its region, with an exceptional historical value and high touristic values. The object constitutes a valuable example of Prussian fortress school from the middle of the 19th century and is one of the best preserved monuments of defence architecture from the 19th century in Poland. The foundation stone was laid on 4 September 1844. The fortress was named “Feste Boyen” after a Prussian minister of defence, Herman von Boyen, who insisted on building the fortress. It is constituted by 6 bastions forming a shape of an irregular hexagon. Names of the bastions were taken from names of gen. Boyen and names on his crest: Herman, Leopold, Ludwig, Sword, Law, Light. The whole fortress is surrounded by the Carnot wall, fortress trench and counter-rampart. Year 1855 was officially recognized as a date of finishing the construction. The fortress can be entered through a two-element gates with neogothic details. The Main Giżycka Gate is the most impressive. The Giżycka Gate, due to its location from the east, is the most fortified one and consists of two passages under the ramparts (posterns) divided by a dry moat and Carnot wall. We have a drawbridge here, entrance to caponier and gate closing the passage into the second postern.