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###Input: There are also many places commemorating the heroic history of Warsaw. Pawiak, an infamous German Gestapo prison now occupied by a Mausoleum of Memory of Martyrdom and the museum, is only the beginning of a walk in the traces of Heroic City. The Warsaw Citadel, an impressive 19th-century fortification built after the defeat of the November Uprising, was a place of martyr for the Poles. Another important monument, the statue of Little Insurgent located at the ramparts of the Old Town, commemorates the children who served as messengers and frontline troops in the Warsaw Uprising, while the impressive Warsaw Uprising Monument by Wincenty Kućma was erected in memory of the largest insurrection of World War II.

Other green spaces in the city include the Botanic Garden and the University Library garden. They have extensive botanical collection of rare domestic and foreign plants, while a palm house in the New Orangery displays plants of subtropics from all over the world. Besides, within the city borders, there are also: Pole Mokotowskie (a big park in the northern Mokotów, where was the first horse racetrack and then the airport), Park Ujazdowski (close to the Sejm and John Lennon street), Park of Culture and Rest in Powsin, by the southern city border, Park Skaryszewski by the right Vistula bank, in Praga. The oldest park in Praga, the Praga Park, was established in 1865–1871 and designed by Jan Dobrowolski. In 1927 a zoological garden (Ogród Zoologiczny) was established on the park grounds, and in 1952 a bear run, still open today.

The flora of the city may be considered very rich in species. The species richness is mainly due to the location of Warsaw within the border region of several big floral regions comprising substantial proportions of close-to-wilderness areas (natural forests, wetlands along the Vistula) as well as arable land, meadows and forests. Bielany Forest, located within the borders of Warsaw, is the remaining part of the Masovian Primeval Forest. Bielany Forest nature reserve is connected with Kampinos Forest. It is home to rich fauna and flora. Within the forest there are three cycling and walking trails. Other big forest area is Kabaty Forest by the southern city border. Warsaw has also two botanic gardens: by the Łazienki park (a didactic-research unit of the University of Warsaw) as well as by the Park of Culture and Rest in Powsin (a unit of the Polish Academy of Science).

In 1939, c. 1,300,000 people lived in Warsaw, but in 1945 – only 420,000. During the first years after the war, the population growth was c. 6%, so shortly the city started to suffer from the lack of flats and of areas for new houses. The first remedial measure was the Warsaw area enlargement (1951) – but the city authorities were still forced to introduce residency registration limitations: only the spouses and children of the permanent residents as well as some persons of public importance (like renowned specialists) were allowed to get the registration, hence halving the population growth in the following years. It also bolstered some kind of conviction among Poles that Varsovians thought of themselves as better only because they lived in the capital. Unfortunately this belief still lives on in Poland (although not as much as it used to be) – even though since 1990 there are no limitations to residency registration anymore.

Throughout its existence, Warsaw has been a multi-cultural city. According to the 1901 census, out of 711,988 inhabitants 56.2% were Catholics, 35.7% Jews, 5% Greek orthodox Christians and 2.8% Protestants. Eight years later, in 1909, there were 281,754 Jews (36.9%), 18,189 Protestants (2.4%) and 2,818 Mariavites (0.4%). This led to construction of hundreds of places of religious worship in all parts of the town. Most of them were destroyed in the aftermath of the Warsaw Uprising of 1944. After the war, the new communist authorities of Poland discouraged church construction and only a small number were rebuilt.



###Question: Why is Warsaw's flora very rich in species?

###Answer: {'answer':'location of Warsaw'}