I will throw Rome here, often overlooked when talking about this stuff, but Rome has the widest green area in Europe, parks, gardens, reserves, green areas in general cover more than 65% of the total surface, totaling 85,000 hectares (~850 km2).
In Berlin in comparison only 30% of the city area is green spaces and woodland, totaling ~260km2.
One of the reasons why Berlin population is 1.2 times larger than Rome, even though the surface of the city is only 70% of the Italian Capitol.
How was that calculated; populations and areas of cities are often calculated in very different ways. You have to show these things on a map and describe why you choose what area and how the population number was calculated. Just "what is a park" differs between cities, even what is a parking space is different. E.g. cars needs a lot of room around them on motorways, that areas is not always counted as "motorway" but can be counted as "green space" in some papers.
I have not seen ANY good examples of comparisions between cities, but I know these problems comes up alot when we discuss cities here on HN.
I've highlighted on the left the area that is actually Rome's territory, Google maps only highlights the area inside the "Grande raccordo anulare" [1], but the city of Rome extends much farther than that, also the area on the beach (the one called Ostia) is actually part of the city even though it is disconnected from it.
That's Rome, the city, then there's the Metropolitan City of Rome Capital [2], which is much larger and includes many smaller municipalities around it, which is in turn smaller than Rome metropolitan area [3]
In Berlin in comparison only 30% of the city area is green spaces and woodland, totaling ~260km2.
One of the reasons why Berlin population is 1.2 times larger than Rome, even though the surface of the city is only 70% of the Italian Capitol.