The castle was erected in the 14th century from the foundation of king Casimir the Great. It was rebuilt in the 15th century, and then twice in the XVI, which was related to the fires that took place here in 1528 and 1541. In 1564 the castle was, however, already mentioned as rebuilt. In 1630 he was burnt down after the riots of hired troops demanding payment of overdue pay. It was subsequently destroyed by the Swedish and Transylvanian armies of Jerzy Rakoczy during the Swedish Deluge. In 1723, starosta Józef Załuski renewed the castle, but it quickly fell into ruin. By the end of the 18th century it was abandoned by the inhabitants, which caused its destruction in the nineteenth century. At that time it was used as a stable. In 1927 the ruins of the castle were secured and in 1946 under the direction of Jerzy Żukowski was renovated and partially reconstructed.
Szydłów Castle was located within the town walls in the northwestern part of the town. Its shape was similar to the rectangle of size 60 X 110 meters, whose outer western and northern sides formed part of the shared line of fortification with the town. On the side of the town, the castle was also separated by a wall, which did not have much defensive significance. Its thickness is only 60-80 cm. The only entrance to the castle was probably from the market, where in the eastern castle wall was a gate, superstructureed in the seventeenth century.
In the north-west corner were two cylindrical towers with a diameter of 10.6 and 10.7 meters, which were a unique solution in the Polish lands. At the south side of the castle at the end of the reign of Casimir the Great or already in the time of Louis of Hungary stood a stone, main house erected on a rectangular plan measuring 12.8×34.8 meters. It had two rooms in the ground floor and two floors with a projection from the south (perhaps a chapel). The building was warmed by a hypocaustum stove. The northern house with dimensions of 15.5×35.5 meters was two-storey and housed three rooms in the ground floor. Its northern wall also marked the line of the northern perimeter wall of the castle.
In the 15th century the castle was rebuilt, which resulted in the replacement of two towers with a rectangular tower, then enlarged with a part with the buttresses, and the line of peripheral walls from the outside was shifted.
To this day, the ruins of the royal palace have been preserved, as well as the so-called Skarbczyk from the 15th / 16th century, which is a redeveloped quadrangle tower, which stood on the site of the former two cylindrical towers, and a baroque gatehouse with remnants of walls separating the castle from the town. On the western side, the castle courtyard is enclosed by peripheral walls, which are also part of the town fortifications.
Leksykon zamków w Polsce, L.Kajzer, S.Kołodziejski, J.Salm, Warszawa 2003.
Późnośredniowieczne zamki na terenie dawnego województwa sandomierskiego, red. L.Kajzer, Kielce 2005.
Wróblewski S., Zamki i dwory obronne województwa sandomierskiego w średniowieczu, Nowy Sącz 2006.