The main seat of the museum is located in the Royal Castle. The first Sanok castle was built by the Polish king Casimir III the Great (Kazimierz III Wielki) after 1341 in a place of the Ruthenian wooden stronghold. A wedding of the king Ladislaus II Jagiello (Władysław II Jagiełło) and his third wife Elizabeth Granowska (Elżbieta Granowska) took place in the castle chambers. The local representative of the royal administration (starosta) of the Sanok county, Mikołaj Wolski, commissioned by the queen Bona Sforza altered the Medieval castle in form of the Renaissance residence between 1523-1548.

The chroniclers wrote an information on a stay of the Hungarian queen Isabella Jagiellon (Izabela Jagiellonka), sister of the Polish king Sigismund II Augustus (Zygmunt II August) (between 1555-1556) in the Sanok castle. False Dmitriy I (Dymitr I Samozwaniec) subsequent tsar, who married Marina Mniszech (Maryna Mniszechówna) a doughter of Sanok starosta, appeared in the castle in 1604.

Numerous alters and demolition of some of the buildings during the Austrian period diminished architectural value of the object. The renovation works, being conducted since the beginning of the 90s, enabled to uncover or reconstruct many Renaissance arrangements and details. The rebuilding works of the southern wing of the castle began in the spring 2010. The works ended in the autumn 2011. Permanent exhibition of Zdzisław Beksiński's works has been arranged in the rebuilt wing.

Ceremonial opening of the new Gallery of Zdzisław Beksiński took place on 18th May 2012. The Gallery has been opened for the public on 19th May 2012. In the first days the exhibition was visited by approx. 10 000 people.

Current revitalization works on the castle hill include, inter alia, erecting the building of conferential hall and stores placed under the surface of the castle court. The castle hill has been surrounded with reconstructed Medieval defensive wall.

www.muzeum.sanok.pl