The castle in Jasiniec was built in the 14th century by the Teutonic Knights on the site of the former hillfort of Pomeranian dukes. A pfleger subordinate to the Świecie commandry resided there. During the Polish-Teutonic wars, due to the border location, castle often changed membership, moving from hand to hand. In 1454 he eventually became the Polish property and became the seat of the eldership, getting into the hands of Jan Kościelecki. During his time there was a reconstruction from the destruction of the Thirteen Years’ War. Further transformations, this time in Renaissance stylistics, were made in the years 1540-1565 under the staroste Adam Walewski. As a result, the castle acquired the character of a comfortable residence, equipped with rare glass windows, painted doors, fireplaces, stoves, etc. In 1773, after the first partition of Poland, the Jasieniec eldership was abolished, and the castle was designated as the seat of the church for Prussian colonists. On this occasion, the ceilings and internal divisions were removed. In the nineteenth century it was finally abandoned and fell into ruin.
The castle was built on the top of the hill on a small peninsula at the edge of the Castle Lake. From the west, it was preceded by an outer bailey on the plan of an irregular polygon, located closer to the base of the headland and separated from the main part of the castle by a moat about 15 meters wide. The defense of the outer bailey was also provided by a moat, while its wall was equipped with a gatehouse and, probably, three four-sided half towers, all located on the north side.
The castle house at the end of the Middle Ages had dimensions of 12.8 x 22.6 meters and was surrounded by a low defensive wall. Its walls were erected up to a height of 5.5 meters from erratic stones bonded with lime mortar, and the higher parts were made of bricks. The entrance to the building was from the west and led through the four-sided projection filling the zwinger space.
Inside, the ground floor housed utility rooms, and the representative rooms were on the second floor, including the so-called “great hall” and a chapel. Above, there was a residential storey with four rooms. The highest, fourth storey with a defensive function was equipped with 22 arrowslits.
The castle has survived in the form of a ruin, deprived of the highest storey and internal walls. The entrance projection is also visible, but the wall around the house and the fortifications of the outer bailey have not survived. The monument belongs to a private investor, but despite his promises, he has not yet undertaken any major security works.
Dzieje Świecia nad Wisłą i jego regionu, red. K.Jasiński, t. 2, Warszawa 1980.
Leksykon zamków w Polsce, red. L.Kajzer, Warszawa 2003.