Question: When did the Soviet Union seal off the city where the creator of the Vegetative Sculpture died?

full_context: Document 1: History of Germany (1945–1990): The intended governing body of Germany was called the Allied Control Council. The commanders - in - chief exercised supreme authority in their respective zones and acted in concert on questions affecting the whole country. Berlin, which lay in the Soviet (eastern) sector, was also divided into four sectors with the Western sectors later becoming West Berlin and the Soviet sector becoming East Berlin, capital of East Germany.
Document 2: Johannes Gutenberg: There are many statues of Gutenberg in Germany, including the famous one by Bertel Thorvaldsen (1837) at Gutenbergplatz in Mainz, home to the eponymous Johannes Gutenberg University of Mainz and the Gutenberg Museum on the history of early printing. The latter publishes the "Gutenberg-Jahrbuch", the leading periodical in the field.
Document 3: Bernhard Heiliger: Bernhard Heiliger (11 November 1915, Stettin - 25 October 1995, Berlin) was a German artist. He was considered "West Germany's foremost sculptor", and his large public artworks are a prominent presence in many German cities, especially Berlin.
Document 4: Way Four: Way Four is a public art work by artist Bernard Kirschenbaum at the Lynden Sculpture Garden near Milwaukee, Wisconsin. The stainless steel sculpture is an open circle that creates an orbit for two triangles; it is installed on the lawn.
Document 5: Berlin Wall: The Berlin Wall (German: Berliner Mauer) was a guarded concrete barrier that physically and ideologically divided Berlin from 1961 to 1989. Constructed by the German Democratic Republic (GDR, East Germany), starting on 13 August 1961, the Wall completely cut off (by land) West Berlin from surrounding East Germany and from East Berlin until government officials opened it in November 1989. Its demolition officially began on 13 June 1990 and finished in 1992. The barrier included guard towers placed along large concrete walls, accompanied by a wide area (later known as the ``death strip '') that contained anti-vehicle trenches,`` fakir beds'' and other defenses. The Eastern Bloc portrayed the Wall as protecting its population from fascist elements conspiring to prevent the ``will of the people ''in building a socialist state in East Germany. In practice, the Wall served to prevent the massive emigration and defection that had marked East Germany and the communist Eastern Bloc during the post-World War II period.
Document 6: West Berlin: West Berlin was 100 miles (161 kilometres) east and north of the Inner German border and only accessible by land from West Germany by narrow rail and highway corridors. It consisted of the American, British, and French occupation sectors established in 1945. It was, however, a de facto part of West Germany. It had a special and unique legal status because its administration was formally conducted by the Western Allies. At the same time, East Berlin, de jure occupied and administered by the Soviet Union, was the de facto capital of East Germany. The Berlin Wall, built in 1961, physically separated West Berlin from its East Berlin and East German surroundings until it fell in 1989.
Document 7: Berlin Wall: The Berlin Wall (German: Berliner Mauer, pronounced (bɛʁˈliːnɐ ˈmaʊ̯ɐ) (listen)) was a guarded concrete barrier that physically and ideologically divided Berlin from 1961 to 1989. Constructed by the German Democratic Republic (GDR, East Germany), starting on 13 August 1961, the Wall cut off (by land) West Berlin from virtually all of surrounding East Germany and East Berlin until government officials opened it in November 1989. Its demolition officially began on 13 June 1990 and finished in 1992. The barrier included guard towers placed along large concrete walls, accompanied by a wide area (later known as the ``death strip '') that contained anti-vehicle trenches,`` fakir beds'' and other defenses. The Eastern Bloc portrayed the Wall as protecting its population from fascist elements conspiring to prevent the ``will of the people ''in building a socialist state in East Germany.
Document 8: Bernhard Mann: Bernhard Mann (born in Stuttgart, Germany, 3 December 1950) is a Social Scientist and Master of Public Health, Professor emeritus of Health and Social Management at the FHM Bielefeld - University of Applied Sciences, former Professor of Health Management and Vice-President at the University of Applied Sciences Bamberg, Adjunct Professor of Public Health, Social Medicine and Sociology at the University of Koblenz-Landau, at the Berlin School of Public Health - Charité, Medical University, at several Universities of Educational Cooperation as well as of Applied Sciences and Public-Health-Coordinator of the german program at the IESS - Institut Européen des Sciences de la Santé Casablanca, Maroc. Since 2018 Mann is editorial member of the World Journal of Public Health. He is a Politician, representative of the Social Democratic Party.
Document 9: Floating Sculpture No. 3: Floating Sculpture No. 3 is a public art work by artist Marta Pan located at the Lynden Sculpture Garden near Milwaukee, Wisconsin. The red fiberglass sculpture is kinetic; it is installed in the pond.
Document 10: Germany: After Germany surrendered, the Allies partitioned Berlin and Germany's remaining territory into four military occupation zones. The western sectors, controlled by France, the United Kingdom, and the United States, were merged on 23 May 1949 to form the Federal Republic of Germany (Bundesrepublik Deutschland); on 7 October 1949, the Soviet Zone became the German Democratic Republic (Deutsche Demokratische Republik). They were informally known as West Germany and East Germany. East Germany selected East Berlin as its capital, while West Germany chose Bonn as a provisional capital, to emphasize its stance that the two - state solution was an artificial and temporary status quo.
Document 11: Bernhard Heiden: Bernhard Heiden (b. Frankfurt-am-Main, August 24, 1910; d. Bloomington, IN, April 30, 2000) was a German and American composer and music teacher, who studied under and was heavily influenced by Paul Hindemith. Bernhard Heiden, the son of Ernst Levi and Martha (Heiden-Heimer) was originally named Bernhard Levi, but he later changed his name.
Document 12: Unfolding (sculpture): Unfolding is a public art work by artist Bernhard Heiliger located at the Lynden Sculpture Garden near Milwaukee, Wisconsin. The sculpture has an abstract form; it is installed on the patio.
Document 13: Axeltree: Axeltree is a public art work by Russian-American artist Alexander Liberman located at the Lynden Sculpture Garden near Milwaukee, Wisconsin. The sculpture is an abstract form; it is installed on the lawn.
Document 14: Vegetative Sculpture I: Vegetative Sculpture I is a public art work by artist Bernhard Heiliger located at the Lynden Sculpture Garden near Milwaukee, Wisconsin. The sculpture has an abstract form; it is installed on the patio.
Document 15: Twist for Max: Twist for Max is a public art work by artist Bernard Kirschenbaum located at the Lynden Sculpture Garden near Milwaukee, Wisconsin. The abstract sculpture is a column of twisting aluminum; it is installed on the lawn.
ground_truth: 1961
sub_queries: Vegetative Sculpture I >> creator Answer: Bernhard Heiliger
What city did Bernhard Heiliger live when he died? Answer: Berlin
when the soviet union sealed off the city of Berlin Answer: 1961