The forerunner of the Museum of Modern History in Ljubljana was Znanstveni institut pri IOOF (the Scientific Institute by the Executive Committee of the Slovene Liberation Front - IOOF), which was founded by the IOOF on 12 th January 1944 ( Act on Foundation of the Scientific Institute by the IOOF, Slovenski porocevalec, year V, No 2, of the 13 th January 1944) on the liberated territory, with a task to "prepare scientific material and scientific results needed by the National Liberation War at present and during reconstruction work after the liberation, as well as to hand on the experience of the National Liberation War to the science itself. (ibid, Article 1)
The Scientific Institute expanded its activities after the war and was renamed the Institute of National Liberation in September 1945. In February 1948, Institut za narodnostna vprasanja (the Institute for Nationality questions) and Muzej narodne osvoboditve LR Slovenije (the Museum of National Liberation of the People's Republic of Slovenia) arose from it (Decision of the government of the People's Republic of Slovenia from February 7 th 1948, Uradni list LRS (Official Journal of the People's Republic of Slovenia), No 7/1948). The museum still attended to its duties, mostly research work, though, it also took over new duties on its founding, among other, " to stage a permanent exhibition, out of the selected material and for the crowds, presenting events and ideals of the National Liberation War" (ibid, article 2, point 5). In autumn 1951, when the museum moved to adapted premises at Cekin mansion, and in 1955, when it staged the first permanent exhibition, it acquired new staff. In addition to a museum department, also an archival, library, historical, and photographic departments, a photo laboratory, and warehouses operated at that time.
In 1959, the museum temporarily lost its name, having become part of Institut za zgodovino delavskega gibanja (the Institute for the History of Workers' Movement). It gained its independent status again three years later, under the name Muzej ljudske revolucije (The Museum of People's Revolution) - Uradni list LR Slovenije, No 20/62. Then, a many years organisation into a museum, fine arts and documentation departments (with a photographic department and a library), as well as a conservation and administration departments, were reestablished. The museum department consisted of the departments for the inter-war period, the Second World War and of the socialism. Such an organisation had far-reaching consequences for the institution, first with the collection of material, and gradually also with exhibition activities.
In the nineties, the museum conformed the adaptation of Cekin mansion to the above mentioned organisation, and launched an action for the renaming of the museum as the Museum of Modern History. A verification of the adaptation plan and the name, the Museum of Modern History, used in all letters and official material of the Ministry of Culture, meant a formal and social confirmation of this orientation. All aspirations of the museum's staff came true by a decision of the Government of the Republic of Slovenia on the foundation of a public institution, Muzej novejse zgodovine (The Museum of Modern History), of May 19 th, 1944 (Uradni list Republike Slovenije, No 28/94).
The Baroque mansion, in which the Museum of Modern history is situated, was built in the middle of the 18 th century by Count Leopold Karl Lamberg. Since then the mansion has changed hands many times. One of the owners was Lovrenc Szëgeny, from whom the mansion's popular name, still used today, was derived. Other well known owners were: governor Pompej of Trieste, Count Brigido, Sigmund Pagliaruzzi Kieselstein and since 1865, Kozler brothers and a sister.
It is known that in 1813, Napoleon's stepson, Italian viceroy, Eugen Beauharnais, lived in the castle. Some years later, in the school year 1818/1819, the famous poet, France Preseren, at that time a tutor of Pagliaruzzi's children, was a regular guest. Speaking of Kozlers, who founded the Ljubljana Brewery in 1864, the Union Brewery today, a lawyer, geographer, member of Parliament, and entrepreneur, Peter Kozler, known to the public mainly as author of the map of Slovenian provinces, is noteworthy. In 1853, the map was confiscated and available to the public only 11 years later.
In the middle of the19 th century, the representative Baroque frontage of the mansion and its beautiful surroundings were one of the Ljubljana regional and architectural sights. At important events, such as the visit of the Emperor or the opening of the railway-station of Upper Carniola, the mansion frontage was lit by torches. From the end of the19 th century onwards, the wast property fell increasingly into disrepair and the mansion slowly lost its former brilliance. After the Second World War, the mansion was occupied by the Ministry of Internal Affairs and the People's Technics. A museum has been housed in the restored castle since 1951.