The archaeological collection dates back to the period 1817-1826 thanks to the excavations, both in the city and in its surrounding, sponsored by the Austrian Emperor and supervised by Michele della Torre Valsassina.
Later on the collection grew up thanks to donations and fortuitous findings such as the discovery, in 1874, in Piazza Paolo Diacono of the so-called tomb of Duke Gisulfo.
At the end of 19th century the Museum venue was in the Palazzo de Nordis and Alvise Zorzi, director of the Museum at that time, defined the first coherent setting of the collection. The Museum changed its name from Royal to State Museum and increased its belongings adding archaeological items coming from the region as well historical documents and art objects.
Starting from 2001 the Museum is under the responsibility of Soprintendenza per i Beni Archeologici del Friuli Venezia Giulia and its core mission is collecting archaeological material with particular attention to Longobard period for which is one of the most important in Italy.