After the establishment of the bishopric in Szombathely, the construction of the ecclesiastic buildings were started. They were mainly in the city centre, in the territory of the church. During these works, a huge number of stone monuments from the epoch of the ancient Savaria has been discovered. These monuments had been shown in the underground chamber of the Bishop's Palace - the Sala Terrena, and in the (then existing) formal garden connected with the chamber. After the bombardment of Szombathely on 4 March 1945, the exhibition was closed.
Several decades later in 1990, after the necessary reconstruction works were made, the Sala Terrena has been opened to the public again. The exhibition has spread into more chambers, where the visitors can see a rich treasury collection. On the walls of the Sala Terrena, the visitors can see a few mythological persons, along with the paintings of the ancient Roman buildings. The paintings on the walls recalls the ancient times and their environment. The frescoes of the salon were made by the painter István Dorffmaister (1725-1797) . His works also shows the stone monuments of the ancient Savaria. In front of the more than two hundred years old frescoes, the visitors can still see some of the ancient stone monuments.