Dating back from 1663, the Kronprinzenpalais was extended beween 1732 and 1733 under direction of architect Philipp Gerlach in the late Baroque architectural style. The second floor was built 19 1856-57 by Johann Heinrich Strack. Following the abolition of the Monarchy in 1919, the Palace was used as home to the Alte Nationalgalerie Collection of Modern Art. The palace was damaged by an Allied bombing in March 1945.
The Act of German Reunification was signed there on August 31, 1990.
The Prinzessinnenpalais (Unter den Linden 5) was first built in 1733 under direction of Friedrich Wilhelm Diterichs. The House of Hohenzollern acquired the Palais in 1788. The connection to the Kronprinzenpalais was erected according to plans by Karl Friedrich Schinkel. The Palace received its name (Prinzessinnenpalais) after its conversion into the home of the daughters of King Friedrich Wilhelm III. The palace served as the Schinkelsche Museum from 1931 unil 1945. Now it serves as the "Opernpalais" (a complex of various dining facilities).