In the head of the castle has dominated a 12m high cylindrical tower, oriented against the access stitch in the southeast. Today it was just a stump. Behind the tower, the miniature core of the irregular ground plan was defined by a perimeter wall. The outer fortification of the castle also included a circular moat, which has been partially preserved on the SE and NW sides. The oldest known modifications include the construction of a new brick fortification. A large bastion of three-circular ground plan called Teres was built in its corner. The highest, originally extended tower from the small castle complex has not been preserved. It succumbed to the ravages of time, as did the rest of the castle complex. The latest building - the Apponyi Palace built in the 16th century - is also well visible. The exterior facade of the palace is dominated by the silhouette of the castle.The defense system consisted of an advanced terrace, whose relics indicate the presence of wood-based (bastion?) fortifications. The firing platform on the SE is protected by another moat and a wall with a semicircular roundel in the middle.

The Opon Castle has appeared in written sources since 1300, when it was in the hands of Master Čák, the brother of Matúš Čák of Trenčín. At that time, it was managed by Čák's castellan komes Valentín, the son of Bohuslav of Trstian. After the untimely death of the master, the castle belonged to Matúš Čák. Another change in ownership did not occur until after Matúš's death in 1321, when the castellan of the castle, Ján, son of Markuš of Výčapiek, handed over the castle to the royal army of Karol Róbert without a fight, led by Mikuláš of the Gutkeled family. In the 14th century, King Sigismund spent a long time here, who later gave the castle in advance. The castle was taken over by Master Dezider Kaplay, who exchanged it with Mikuláš of Čeklís. After 1392, it was acquired by the daughters of Mikuláš of Čeklís and their husbands. Of these, after the division of property in 1395, Peter, the son of Tomáš of Stráž, became the sole owner of the castle. Peter, the founder of the Apponyi family (Oponick family), helped to increase the castle estate and the castle itself. Peter's sons Tomáš and Mikuláš also continued to expand the economy on the estate.

During the 15th century, individual members of the family built comfortable mansions in the village below the castle - therefore, in 1514, the people of Anna Ludanická from Ludaníc managed to raid and rob the castle. The castle became a more permanent seat of the Apponyi family again only during the Turkish invasions. The rapidly growing Turkish danger and the poor condition of the damaged castle led Benedict Apponyi in 1542 to decide to restore the castle. Subsequent disputes with the co-owner of the castle probably slowed down the whole restoration, because in 1566 the widow of Benedict, who owned most of the castle, had to back up her amount to Ján Apponyi due to lack of money for fortification work. The extensive reconstruction of the castle almost completely replaced the older medieval structures with new, mostly residential representative buildings with decorations in the style of the late Renaissance. According to the use of morphological architectural elements in the reconstruction, we date it around the beginning of the 17th century, when Pavol Apponyi was one of the co-owners of the castle - one of the most important personalities of the family. Such a fortified castle protected the owners from the Turks, but the Turkish looting did not escape the castle, which they burned down together with the church.

In 1645, the neglected and unmaintained castle was damaged by fire, and the castle served as a military facility for the last time, allegedly when the Kuruk insurgents were hiding in it. The castle was then probably blown up by the Turks or completely destroyed during the Rákóczi uprising.

There are no myths available.

The ruins are freely accessible

https://www.hrady-zamky.sk/oponicky-hrad/