Question: Which city is a home to OPEC and birth place of an Australian community worker, internee, Lutheran pastor and refugee?

Context articles: Heinrich Christian Schwan
Elizabeth Platz
Annie Forsyth Wyatt
Vienna
Mary V. Austin
Rita Buxton
Helena Marfell
Alfred Freund-Zinnbauer
Monica Gallagher (community worker)
Helga Josephine Zinnbauer

Heinrich Christian Schwan (April 5, 1819 – May 29, 1905), a German Lutheran pastor, was the third president of the Lutheran Church–Missouri Synod (LCMS), from 1878 to 1899.
 He earlier served as a missionary in Brazil, as a pastor in Cleveland, Ohio, and as president of the synod's Central District.
 Schwan is credited with being the first pastor to erect a Christmas tree in an American church sanctuary and was responsible for the Missouri Synod's first exposition of Martin Luther's Small Catechism.
 He was the son of the Rev. Georg Heinrich Christian Schwan, an Evangelical Lutheran pastor in northern Germany, and his first wife, Charlotte Wyneken, and was also the half-brother of Major General Theodore Schwan.
The Rev Elizabeth Alvina Platz is an American Lutheran pastor and was the first woman in North America ordained by a Lutheran church body.
 She was ordained in November 1970 into the Lutheran Church in America (LCA).
 The ordination of women, approved earlier that year by both the LCA and The American Lutheran Church (ALC) was controversial.
 The ALC ordained its first woman as a pastor, the Rev. Barbara Andrews, in December of the same year.
 The ALC and LCA merged in 1988 with the Association of Evangelical Lutheran Churches to form the Evangelical Lutheran Church in America (ELCA).
Annie Forsyth Wyatt (3 January 1885 – 27 May 1961) OBE was an Australian community worker, conservationist and Red Cross worker.
 She is celebrated as the driving force behind the establishment of the National Trust movement in Australia, establishing the organisation in 1945 to protect Sydney's historic natural and built sites.
Vienna ( ; German: "Wien" , ] ) is the capital and largest city of Austria and one of the nine states of Austria.
 Vienna is Austria's primary city, with a population of about 1.8 million (2.6 million within the metropolitan area, nearly one third of Austria's population), and its cultural, economic, and political centre.
 It is the 7th-largest city by population within city limits in the European Union.
 Until the beginning of the 20th century, it was the largest German-speaking city in the world, and before the splitting of the Austro-Hungarian Empire in World War I, the city had 2 million inhabitants.
 Today, it has the second largest number of German speakers after Berlin.
 Vienna is host to many major international organizations, including the United Nations and OPEC.
 The city is located in the eastern part of Austria and is close to the borders of the Czech Republic, Slovakia, and Hungary.
 These regions work together in a European Centrope border region.
 Along with nearby Bratislava, Vienna forms a metropolitan region with 3 million inhabitants.
 In 2001, the city centre was designated a UNESCO World Heritage Site.
 In July 2017 it was moved to the list of World Heritage in Danger.
Dame Mary V. Austin (née Hall-Thompson; 29 July 1900 — 10 September 1986) was an Australian community worker and political activist.
 The daughter of Admiral P. H. Hall-Thompson and his wife, Helen (née Deacon), she was educated in New Zealand at Marsden College, Wellington.
Dame Rita Mary Buxton, DBE (21 November 1896 – 22 August 1982) was an Australian community worker, activist, racehorse owner and philanthropist.
Helena Catherine Marfell OBE, "née" Glen (4 August 1896 – 2 November 1981) was an Australian community worker who was the first president of the Country Women's Association of Australia (1945–1947).
Alfred Freund-Zinnbauer MBE (26 June 1910 – 9 November 1978) was an Australian community worker, internee, Lutheran pastor and refugee.
 Zinnbauer was born in Vienna, Austro-Hungarian Empire (Austria) and died in Adelaide, South Australia.
Dame Monica Josephine Gallagher, DBE, DCSG (née McInerney; 5 April 192318 September 2013) was an Australian community worker and church activist.
Helga Josephine Zinnbauer (24 February 1909 – 16 December 1980) was an Australian community worker and librarian.
 Zinnbauer was born in Orsova, Austria-Hungary (now Orșova, Romania) and died in Adelaide, South Australia.