The noble family Coronini von Cronberg built the castle, presumably in the early 17th century (1609), partly on the foundations of an older castle from the 13th century. The two-storey castle building is Renaissance in design and appearance. It consists of a central building with an almost square floor plan, with four towers at the corners. The castle burned down in both world wars. The fire destroyed the interior furnishings, library and archive. The castle underwent extensive renovation work after 1954, when the Gorizia Museum moved into it.
In the castle park and the ground floor entrance hall there is a small lapidary, which contains several coats of arms of the noble families of Gorizia.
On the first floor there is a permanent exhibition of the art history and cultural history department: a gallery of ancient art, a cultural history department with an emphasis on 19th century painting with paintings by Franc Kavčič and Jožef Tominec. The main space in this part is intended for weddings. On the second floor, there are occasional thematic archaeological, historical and ethnological exhibitions.
The purpose of the museum collection at Kromberk Castle is to provide at least a partial picture of the historical, cultural and social development from ancient times to the present day in the area of ​​operation of this institution.