When in Osterode created self-Comtat in further expeditions south of the Teutonic Order was needed more extended in the direction of Mazovia and Kujaw stronghold. Around 1350 years Winrych commander von Hohenstein started building the fortress in Olsztynku, which lasted for 1370 years. Probably existed here before the strengthening of wood, but they were not sufficient.

The castle had a rectangular plan - three residential wings of brick on a stone foundation surrounded the courtyard closed from the south wall. Most impressive was the northern wing, where they lived religious officials, along adjacent to the other two wings ran from the courtyard cloisters.

Further south, housed a small ward. The castle was surrounded by an additional second sequence of the peripheral walls with corner towers and a moat. In 1359 years south of ward has been invested in the city, which was surrounded by a palisade.

As for the layout of the rooms, the mention of the fifteenth century mention the chamber bailiff religious, kitchen, bakery, basements and barns in the attic. This completes the picture record of 1516 years, from which we learn that in the south wing was also a refectory, an armory and living room.

After the Battle of Grunwald castle in Olsztynku has included 18 lipca king Jagiello 1410 years, when he moved to Malbork. The castle was Prince Janusz and senior crew. After the Peace of Thorn, however, Olsztynek back in the hands of the Teutonic Knights. In 1414, during another war with the law, Olsztynek again surrendered without a fight, however, before the withdrawal of the Crusaders burned down the town and castle. And this time, quickly returned the boundaries of the Teutonic Order.

In 1440 Olsztynek joined the Prussian Union, and when the war broke out in 1454, Poland lost the battle at Chojnice, the City Council decided to surrender to the Teutonic Knights. During the last war with the Order Olsztynek again fell into the hands of Polish in the December 1519 year. After the secularization of the Order in 1525 areas have been incorporated into Prussia.

During the Swedish wars provided an arsenal here, probably in the ward.

Be the first image of the castle is known figure Hartknoch 1684. Then already been partially dismantled fortifications. Demolished a wall surrounding the castle and ward buildings combined with the city. By the end of the seventeenth century, yet liquidated most Gothic elements of the defense, with elewecji disappeared slits replaced by a rectangular window. Then the castle is not too carefully looked after and during the eighteenth century fell into disrepair and in 1793 a year, most walls were demolished. From the main southern wing remained only the ground floor, designed for housing officials, the remaining portions of the western wing it.

In the years 1847-1849 using the gothic walls attempted to reconstruct the castle, which has become neo-Gothic features.

The restored buildings placed school. During the world wars, the castle walls have not been spared, but in the years 1946-1954 it was rebuilt and re-submitted for the purposes of education.

Few preserved remains of the Middle Ages, although very easy to read the general assumption in the basement preserved Gothic vaults.