Diocesan Collection and Visitor Center János Szily
János Szily, the first Bishop of Szombathely (1777–1799) gathered ancient Roman stone relics discovered in Szombathely and surroundings and exhibited them in the Sala Terrena of the Episcopal Palace. According to our present knowledge, this was the first acheological museum in Hungary, since the intention of the Bishop was obvious: he wished to preserve and to exhibit the archeological findings. The frescoes (1784) depicted by Stephan Dorffmaister decorating the walls of the Sala Terrena are also telling, since they represent the Roman stones exhibited in the hall in lifesize. According to the correspondence between János Szily and the former jesuit, Stephan Schönvisner (1780's), at that time director of the University Library in Budapest, prove that the Bishop commissioned a monograph about the history of Szombathely. Schönvisner's book, entitled Antiquitatum historiae Sabariensis…libri novem has been published in Budapest in 1791. Schönvisner made a proper scientific description about the Roman ruins of Szombathely as well as about the coins from the Bishop's numismatic collection.
In 1872 the Archaeological Society of Vas County was founded, presided by Bishop Imre Szabó (1869–1881). The secretary of the newly founded society was the Norbertine canon Vilmos Lipp, while the prestigious historian, Flóris Rómer, at that time director of the Archaeological Department of the National Museum, was asked to become honorary president. After Bishop Szabó generously donated the sala terrena to the Archaeological Society, showcases displaying various archaeological materials were set along the walls of the room. In 1908 the Vas County Museum opened its gates, so the archaeological findings were transported into the museum.
One had to wait until the period between 1911–1935 for a patronage comparable to the one by Bishop János Szily. At this time the Diocese was governed by bishop János Mikes of Zabola (1875–1945). Stemming from an old Transilvanian family, the bishop had vivid connection with Switzerland and Germany, from where his mother, Sophie Moser descended. During his stay in Szombathely, János Mikes restored the Episcopal Palace, introduced electricity, covered the walls with wallpaper and embellished the palace with fine pieces of furniture and works of art. It is a known fact, that he was in connection with the Bernheimer art dealer Company in Munich and that he often saved furnishings from aristocratic residences, for example from the castles of Zsira, Hegyfalu and Mezőnyárád. He purchased several artworks during his journeys in Europe and all around the world. He was vice-president of the Museum's Friends Society (Múzeumbarátok Egyesülete) founded in 1913. He asked for protection of the interiors and furnishings of the Episcopal Palace from the Central Office for the Protection of Historical Monuments (Műemlékek Országos Bizottsága). He was the first initiator of registrating the monuments and artworks to be found in the Diocese of Szombathely. In all his work he has been supported by his collaborator, Gyula Géfin, director of the Diocesan Library and chronicler of the Diocese.
After the serious damage caused by the Second World War, in 1950 the artworks and furnishings of the Episcopal Palace were placed under monumental protection. In the 1970s specialists of the Hungarian National Museum and the Applied Arts Museum visited all Episcopal centres and made an inventory of those objects which were considered valuable and made also a description about them. In the Diocese of Szombathely this work was done by Emőke László and Erzsébet Vadászi from the Applied Arts Museum, who described the textiles and furnishings, and Judit Kolba and Zsuzsa Lovag from the Hungarian National Museum who registered the goldworks.
The right wing of the Episcopal Palace, destroyed during the bombardment on 4 March 1945, was reconstructed in 2016, during the celebrations commemorating the birth of Saint Martin of Tours, the patron saint of the Diocese. The treasury, originally exhibited on the ground floor, in the rooms adjacent to the Sala Terrena, was moved to the first floor, to the antechamber giving access into the baroque halls. The walls of the antechamber are decorated by three oil sketches made by Franz Anton Maulbertsch for the side-altar and the frescoes of the Cathedral of Szombathely. The rooms open to visitors on the first floor of the palace are the Cabinet of Engravings, the Bishop's Portrait Gallery, the Grand Hall, The Mikes or Yellow Room, Saint Paul's Room, Red Room, the Library Room and the Private Chapel. From 2017 the Diocesan Collection of Szombathely bears the name Diocesan Collection and Visitor Center János Szily.