Despite the far-reaching independence of the city government, the order’s authorities effectively watched over their subjects. The strategic location, allowing control of the water and land routes, determined the unique military features of the convent house and the fortification system of the city and castle. The fortress was built in the Gothic style on a square plan with an internal courtyard and a well. It had three turrets and one larger defensive tower. The original gate was located in the southern wing.

There was a refectory in the northern wing, and a chapel in the southern wing.

The eastern part probably housed the commander’s room and a dormitory. The entrances to the main rooms on the main floor led from the cloister running along the walls inside the courtyard. There were kitchens and utility rooms on the ground floor. The castle was surrounded by a water-filled moat and defensive walls. An old story says that there were also underground corridors leading from the castle into the city. As late as 1856, in the southern corner, between the castle and the trench, there was a round tower with a circular staircase leading to the level of the moat and connecting with a corridor, which in turn led on the western to the basement in the city.

In the XVth century, the castle was partially rebuilt. During the Thirteen Years’ War in the second half of the XVth century, and then during the Swedish wars in the XVth century, the stronghold was partially destroyed. In the XVIIIth century, the castle lost its defensive functions, was not renovated and was abandoned.

After Gniew was taken over by Prussia in 1772, it was rebuilt into grain warehouses. It caused significant damage to the interiors, the Gothic vaults were demolished, the original window openings in all facades were removed (they were plastered at the same time), the latrine tower – “Dansker” – was demolished, the moats around the castle were filled in and an additional gate opening was carved in the western wing. Partial reconstruction was carried out in the years 1857-1859 when it was established as a heavy Prussian prison for recidivists. At a cost of 133,397 thalers 23 and 1/4 groszy, the chapel’s vault was reconstructed and the original ogival shape of several window openings on the southern façade was restored, thus significantly improving the image of the castle from the south. The two corner towers were also rebuilt. In 1920, Gniew was incorporated into the Polish-Lithuanian Commonwealth.

The Polish administration sits in the former prison, and later the facility is taken over by the army. In 1921, in unexplained circumstances, a fire broke out in the castle, destroying the roof and three wings. Since then, the castle has remained in a state of secured ruin. During World War II, it was a transit camp for the Polish population from Pomorskie. After the war, the Electronic Components Plant was opened here, and in 1969, the local Ship Mechanism Plant “FAMA” began preparing documentation and implementing the project of adapting the southern and eastern wings of the Castle for its cultural and social purposes.

The upper part of the walls was then repaired, the steel and reinforced concrete structure of the roof was constructed and it was covered with ceramic roof tiles. The developing investment came to an end in the mid-1970s. Further renovation works started in the 1990s. Their initiator was the castellan of Gniew Castle, Jarosław Struczynski. As part of public works in the years 1992-1997, it was possible to raise the castle from the rubble, bringing it to its current shape.

Since 2010, the castle complex has been managed by the Polmlek Group. During this time, the buildings included in it were restored and the whole was transformed into an international center of culture, tourism and historical education. Marysienka Palace offers comfortable relaxation in stylish chambers, a modern, four-star Rycerski Hotel was built in the former barracks, and the covered courtyard of the castle is an extraordinary space with an area of over 450 m², serving as a concert, conference and banquet hall.

Tradition obliges, which is why the fortress has been famous for years for its battle reenactments, knights’ tournaments and historical performances, performed in the beautifully landscaped grounds of the castle. The pillar of the reconstruction activity are equestrian groups: the Hussar Banner of the Marshal of the Pomorskie Voivodeship, bringing together several dozen people involved in the reconstruction of the XVIIth century hussars, considered one of the best cavalry formations in Europe, and the Gniew Castle Knights Team, constituting a several-person Polish representation in the International Jousting League, bringing together approximately 200 players from 17 countries. The Horse Knight Tournament organized in Gniew received the highest rating in the entire League for the quality and level of performance. The castle also houses the Yellow Infantry Regiment of Gustavus II Adolphus and the Schola Cantorum Gymevensis choir – the only amateur, secular Gregorian choir in Poland.

The trend of castle life can give an injection of positive energy. In the European Historical Park, in the shadow of the castle walls, everyday life of a medieval town takes place. In a wooden workshop, a potter is making clay vessels on a spinning wheel, in a neighbouring house, colorful fabrics are made from the skilful fingers of a weaver, and a tall blacksmith is making horseshoes with skilful movements. Ladies of the court walk among the workshops and huts, and knights practice sword and spear skills.

To get to know the natural values of the Lower Vistula Valley, you can go on a bicycle trip, a gondola cruise or a carriage ride. The queen of Polish rivers has carved out a beautiful valley here with numerous oxbow lakes, rich in rare species of flora and fauna. Gniew Castle is a magical place where history combines with high quality tourist services.