After Lithuania regained its independence following World War I in 1918, the Schlossberg's house became the headquarters of the army. It soon was captured by Polish troops following the Polish annexation of Vilnius. During World War II, it was the office of the German Wehrmacht, and after World War II it was used by Soviet security structures and later transformed into a Respublican Pioneers Palace. Pioneers' organisation vacated the building by the 1987. Archeological excavations started on the site, because Schlossberg's house was proposed for the People's Friendship Museum and for this conversion architectural investigation were needed to take place.