north. After the unification of Germany in 1871, the building was mainly used for housing soldiers and for storage. In 1912–1913 it was remodelled and expanded with a neo-Baroque style mansard roof and the addition of large dormer windows on both sides of the building. After this it was then able to accommodate 750 soldiers. After the end of World War I in 1918, as a result of the Treaty of Versailles in 1919, there was gradual decline in use of military facilities in Germany. The barracks was used as residential building and as quarters for the civil police and the Freikorps Thüringen, a civilian militia army unit. During the rearmament of the army during the Nazi period, there was renewed military use of Petersberg citadel. From 1936 to 1938 part of the barracks was used to house the new established Motorized Infantry Regiment no. 71, and from 1938 to 1939 as the headquarters of the army's administrative offices. In 1944 a transit camp for displaced people was established in the Defense Barracks, and this was continued by the occupying Soviet administration after the war. When the German Democratic Republic (East Germany) was founded in 1949, the citadel again was used by the military. The Defense Barracks was used to accommodate a police school, the Kasernierte Volkspolizei (a precursor to the Nationale Volksarmee - NVA), and after 1956 newly formed NVA. After 1963 the citadel became the property of the city of Erfurt and the Defense Barracks were used for storage. It has been vacant since 2000 and there is on going discussion about how it will ultimately be restored and used. Barracks A (Kaserne A) Barracks A was built in 1675. The 94 meter long building is a terrace of four houses with separate entrances and a central portal providing access to a back courtyard. It was used as a barracks until the end of World War I in 1918. After that it was used for civilian housing. From 1935 to 1945 it housed the Wehrbezirkskommando (District military command headquarters). From 1945 it was an old people's home. The building was restored between 2000-2001 and it now houses a mixture of private apartments and offices. Lower Barracks (Untere Kaserne) The Lower Barracks was built c.1690. It now houses the Stasi Records Agency, officially the Bundesbeauftragt für die Stasi-Unterlagen (BStU). It provides exhibitions and public guided tours, in German, every