At that time, old Teutonic castles in Rogóźno and Grudziądz were dismantled for the needs of the fortress, and the foundations of both sides of Bastion I were built with stone.

There were also technical difficulties in setting up terraces and ramps on the Vistula escarpment – numerous springs and streams flowing from the mountain made the work challenging.

However, this estimate quickly proved unrealistic, even though construction of some of the previously planned anti-mine tunnels, designed to destroy siege works, was abandoned.

By the end of 1806, the Prussian forces were augmented by three infantry battalions and one squadron of hussars, and additionally, the Citadel had strong artillery (154 cannons, 35 howitzers, and 16 mortars).

At the beginning of January 1807, a unit of Polish insurgents led by Major Dominik Dziewanowski appeared on the left bank of the Vistula.

At the end of January, a company of infantry under the command of Captain Jan Barankiewicz appeared near Grudziądz, occupying Wielki Lubień.

After Russia entered the war and achieved temporary successes in East Prussia, the forces of the Grande Armée withdrew from the conquered territory.

The desertions from the Prussian units were exacerbated by the arrival of the Polish 11th Infantry Regiment in Wielki Lubień, commanded by Colonel Józef Wasilewski with a force of 1,600 men.

The siege was halted upon news of the armistice following the Battle of Friedland (June 14), due to negotiations preparing for the Treaties of Tilsit.

On 30 April 1862, a mutiny of Prussian soldiers of Polish nationality broke out under the command of Gotfryd Klatt, but it did not lead to significant consequences.

However, the function of the fortress was reinstated twice for the city: after the construction of a bridge over the Vistula river between 1876 and 1888, and on 1 September 1944, due to the approach of the Red Army.

[4] Soviets and Poles grouped in units of the 2nd Belarusian Front under the command of General Pavel Batov engaged in bloody battles for the city from the end of January until 5 March 1945.

[5] In some actions, other forts of the Fortress were utilized, such as Dąb and Strzemięcin, but the Citadel itself remained a rear base for occupying forces.

German units were defeated and took refuge in the Citadel; however, realizing the futility of further resistance, Major General Ludwig Fricke signed the surrender document on March 6.

Within the bergfried, the best-preserved and most characteristic feature is the two-story Great Warehouse, as well as the neoclassical former commandant's building located in the middle of the courtyard.

It filled the gap between Księża Góra and Kępa Forteczna and served as protection for the entrance to the city from the Olsztyn side.

Unlike other shelters in the inner ring, it was adapted for self-defense, with a latrine protruding in front of the facade to create a sort of caponier.

Located beyond the intersection of roads leading to Olsztyn and Malbork, near Klonowa Street and close to allotment gardens, lies Fort Tarpno.

Inside the ramparts stands the barracks shelter, worth visiting due to its minimal degree of devastation, with bossages around the door and window openings.

Inside, one can find equipment elements from the time of construction, such as the base for a diesel generator and inscriptions on the walls in German.

One of the guardrooms has a preserved ceiling reinforced with corrugated sheet metal.The battery was situated north of the Citadel and had an earth construction.

The length of the fort was approximately 600 m. The rampart was defended frontally by infantry fire and ten 53 mm cannons in portable armored towers (Fahrpanzer), placed in previously prepared crescent-shaped concrete positions.

Access to the fortifications was from the current Droga Graniczna Street.In 1892, an infantry bunker was built for 90 soldiers, made of brick and concrete.

On the high bank of the Vistula river near the no longer existing Strzemięcin folwark, large-scale fortification works began at the end of the 19th century.

During a visit, one may come across a dry moat, retaining walls, and even posts with visible barbed wire in several places, as well as an artillery battery consisting of mobile guns in turrets (Fahrpanzer).

At that time, a German garrison under the command of Captain Friedhausen, consisting of 8 officers and 102 soldiers, resisted Soviet forces for several days while surrounded, until running out of ammunition.

Next to the battery, on its right wing, you can see an aerial target trap, built in 1940, used to check the accuracy of machine guns installed in Messerschmitt Bf 109 and Focke-Wulf Fw 190 fighter planes undergoing maintenance at nearby aircraft factories.

The fort, located on the western side of the road to Radzyń, was equipped with a powerful bunker for 280 soldiers, featuring 2.5-meter walls and a 3-meter ceiling designed to withstand hits from 420 mm caliber shells.

[8] Situated in Las Miejski, the ramparts are currently well-preserved, with remnants of stakes in the moat for securing barbed wire.

They were protected from the front by a concrete parapet, a flat rampart, and a shallow moat equipped with barbed wire and a fortress grille.