The Jazłowiec castle was notable for its early construction date. The fortified residence dates back to the 14th century and was built for the owners of the estate, who used the surname Jazłowieccy. Jerzy, who lived in 1510-1575 and was Grand Hetman of the Crown and Castellan of Kamenz, was a descendant of this family and it was on his initiative that the castle was extended by adding a four-storey tower with a gate passage. Later, the castle passed into the hands of various families (including the Czuryłów and Bełżeccy families), and finally became the property of Hetman Stanisław Koniecpolski, who purchased it from Anna Odrzywolska in 1643.

From the Koniecpolskis to the Potockis
At the time when Stanisław Koniecpolski took over, the castle in Jazłowiec fitted into the model of traditional fortified construction, being one of the oldest examples of fortresses in Podolia. Thanks to the use of natural conditions - its location on a high promontory - the building fully fulfilled its defensive functions, which is why the hetman (despite having a huge fortune at his disposal) did not decide on major reconstruction. Security was ensured, among other things, by bastions formed in the 16th century, which still effectively protected the castle and its crew.

After the death of Stanisław Koniecpolski, the estate of Wežłovice passed into the hands of his son, Aleksander, who took a number of measures to strengthen the fortifications of the town, which was frequently invaded by Turkish troops. The castle complex, probably extended between 1649 and 1658, was given an irregular outline. Mainly stone was used as building material, supplemented by brick. The buildings were divided into two areas: the upper castle (the older one, located on a promontory facing east) and the lower castle connected to it by a bridge. The courtyard was surrounded by a wall, with towers to the east and bastions adjacent to the curtain walls to the north and south. A response to the position and ambitions of the owner was also the construction of a new, two-bay wing within the complex, intended for residential (residential and parade) functions. Significantly, the Koniecpolski castle was perfectly suited to defending itself against invaders, defending itself longer and more effectively than other borderland fortresses, which was evident, for example, during the Turkish offensive in 1671. When the hostile armies, having a considerable numerical advantage over the fortress crew, managed to capture Jazłowiec, it was quite quickly recaptured by the Poles - in 1673 after the Battle of Chocim (after a year from the capture of the castle by the Bashas) and in 1684, during the expedition of King Jan III of the Sobieski family.

New realities - the primacy of Kamieniec and the loss of importance of the Hetman's castle
The next century brought a decline in the importance of the fortress, even though the estate was managed by significant families. From the beginning of the 18th century, Jazłowiec belonged to the Lubomirskis, after whom, in 1746, the lands were taken over by Stanisław Poniatowski - the father of the future king of the Republic. Several factors contributed to the loss of the castle's earlier status, one of which was the recapture of Kamieniec Podolski in 1699. Kamieniec Podolski (which took over the leading military role on the borderland). At the same time, an important reason was the need for a residence that corresponded to the current fashion, adapted to the needs of the owners. The Poniatowskis therefore decided to build a new, three-winged palace, erected on the site of the former lower castle. The history of Jazłowiec is also strongly connected with the presence of the Sisters of the Immaculate Conception of the Blessed Virgin Mary, who, from 1863, managed the former residence complex, adapting it for use as an educational institution for children and a grammar school with a boarding school for girls. With the change of function, the most urgent restoration work was carried out - unfortunately only the palace, much better suited to the needs of this type of institution, was included. Already at the end of the 1850s, the castle was described as severely deteriorated, despite the preservation of the original form of its masses, which included towers, underground dungeons, vaulted rooms and ramparts surrounding the building. Attention was also drawn to the fact that, for example, the main tower, which was heavily damaged, could easily be salvaged and restored to its appearance from its heyday. Unfortunately, the ideas of restoration and partial reconstruction were not realised. To this day, all that can be admired are the remains of the upper castle with its tall, massive tower and relics of richly decorated stonework (portals, window frames).