The fortress was an innovation in terms of its architecture. It was the first building of this type to feature the fortification system later known as the "new-Prussian" system, co-developed and elaborated on in theoretical terms by Leopold Brese.
The first step to accomplish these plans was to move two villages, Winiary and Bonin, situated on Winiary Hill towering over the city, i.e. right in the spot where the Citadel (Winiary Fort) was to be erected. The construction works began on 23 June 1828 with the digging of ditches for planned moats. The works proceeded very slowly, but were carried out with Prussian orderliness. The construction materials were delivered from brickyards situated in Wilda, Rataj, Przepadek, Radojewo, Promnice and Żabikowo. All finished buildings were instantly armed and garrisoned. As early as on 1 October 1834, Fredrick William III of Prussia rates Poznań among class II defensive fortresses. In December 1834, the whole redoubt with barracks, Kernwerk, which it the central part of the fort, designed by Major Johann Leopold Ludwig von Brese (1787-1878) was put to use. The general shape of the Citadel fortification was formed around 1842, but the final silhouette of the fortress was still being worked on in the 1870's by the prisoners of war. At the time, it used to be the most central element of the inner polygonal fortification ring surrounding the city (today's city center).
The Citadel, built according to the new Prussian system, covered the area of approx. 100 ha. The outer embankments with moats were built on the plan of a polygon. The Kernwerk consisted of three-storey barracks with basements, with two observation towers with artillery decks at the back of barracks. It could be reached by two bridges: the main bridge, for the artillery and the one for the infantry. From the south, the redoubt was protected by two sluices: the Small Sluice on the Wierzbak River and the Great Sluice on the Warta River. They ware able to swell waters and create pools on the fortress outskirts. At the ends of both sluices the following forts were situated: Wojciech's Fort (Hake Fort) at the Small Sluice and Bridgehead (Roon Fort) at the Great Sluice. The whole fortress was surrounded by main earth embankment, fortified on the north side with three bastions and four protruding ravelins, and from the south side, the barrack rooms were flanked by fire from four independent redoubts. The external defense line was 3 km long. The Citadel was surrounded by a dry moat 6-32 m wide and about 7 m deep. All buildings had brick walls 1.3-1.8 m thick. The whole fortress complex was surrounded by so called "covered path", which lead around it on a battle slope.
In 1839, King Frederick William III consented to the erection of fortifications surrounding the left-bank part of the city. It was composed of 6 bastions and 2 forts connected with earth defenses. They were finished in ca. 1860.
Throughout its history, the fortress performed various functions. Here the Polish conspirators after the uprisings in 1846, 1848 and 1863 were imprisoned (including L. Mierosławski, W. Niegolewski and W. Stefański), and prisoners of war after the wars with Denmark (1864), Austria (1866) and France (1870-71), which brought victory to Prussia.
Fast technological progress in the art of war in the second half of the 19th century contributed to the weakening of the importance of the Citadel. As a result, in the years 1876-90, a new external ring of forts was built on the city outskirts, which assumed the role of earlier fortification.
In 1902, Emperor William II consented to the demolition of the fortifications at the outskirts of the left-bank city, except for the Citadel. His decision was prompted by the fact that, at the time, this type of fortification was not very useful from the military point of view and his intention to transform Poznań into a residency city (Residenzstadt).
During World War I, the Winiary Fortress did not play any role in the military actions. Captured without battle by the Wielkopolska (Greater Poland) Uprising insurgents (29 December 1918), it became the center of the formation of the First Greater Poland Rifle Regiment and the First and Second Telegraphic Battalions. The capture of the fortress radio station from the Germans was of great importance; it enabled the insurgents to contact Warsaw and other European capital cities directly. In the interwar period, the Citadel was the place where the Polish army units were stationed, such as the Seventh Telegraphic Battalion, the Seventh Sanitary Battalion, the Twelfth Railway Battalion, the Seventh Administrative Battalion, the Seventh Convoy Cavalry Troop and the Third Railway Army Regiment. Thanks to the effort of the soldiers of the last unit mentioned above, on 21 July 1923, the narrow-gauge railway 17.4 km long, linking the Citadel with the Exercise Camp in Biedrusk, was put to use. The fortress had also a working transmitter of the local Polish Radio Station (since 1934) and direction-finding and listening station No. 4, operated by the Eleventh Unit of the Chief Staff of the Polish Army, which was engaged in radio intelligence aimed at Germans.
Following the capture of Poznań by Wehrmacht (on 10 September 1939), the fort was used as prison for prisoners of war - first the Polish ones (e.g. Brigadier General Roman Abraham), then the British and Russian ones, and the south-west part of the moat was used as an experimental shooting-range for Deutschen Waffen- und Munitionsfabriken AG (H. Cegielski) plant. The military importance of the Citadel increased unexpectedly in the years 1944/45. It became the main resistance point for the German several thousand strong crew of Festung Posen. When captured on 23 February 1945, after a five-day storm, it took a death toll of several hundred soldiers and officers of the Red Army and Poznań residents (so called Citadel fighters), recruited by Russians. It was the first and, as it later turned out, the only war episode in the history of the fortress. During the war, the redoubt with barrack rooms was partly destroyed; other parts survived almost intact.
After the end of World War II, the city authorities decided to demolish the Fort. It was done in the years 1950-58. The bricks were used to rebuilt the housing estates in Poznań (e.g."On Dębiec" Estate and the estate at Chociszewskiego Street) and in Warsaw. From 1962, the Citadel had been turned into Monument Park of Polish-Russian Friendship and Brotherhood of Arms (today, it is called the Citadel Park). In 1962, the remnants of the fort architecture were entered in the State Register of Historical Monuments. Today, the Citadel constitutes most of all conveniently located "green lungs" of the city, with a complex of military cemeteries, monuments, sculptures (e.g."Unrecognized" by Magdalena Abakanowicz), the Bell of Peace and Friendship between Nations and two museums (Museum of Armaments and Museum of the "Poznań" Army), situated in partly restored fort buildings.