Melbourne, Victoria has a large number of people with Greek heritage. It often has claims that its Greek population rivals cities in Greece. For example:
By 2004 Melbourne's Greek community was considered the largest outside Greece, and third only to Athens and Thessaloniki, with estimates numbering the first, second and third generations at approximately 300 000.
Greek Reporter quoted a statistician in 2010 who put it seventh:
Melbourne no longer is the 3rd Greek- speaking city in the world, if ever it was… [...] “the allegation that Melbourne is ranked 3rd Greek-speaking country in the world, does not correspond to actual facts. According to official data, Melbourne is occupying the 7th position, preceded in order by Athens, Thessaloniki, Piraeus, Patras, Nicosia, Limassol and followed by Sidney. Perhaps some cities of the US (Chicago and New York) have more citizens of Greek origin, but in Melbourne, most Greeks also speak Greek.
In 2004, The Age discussed the debate:
[Greece Now] estimates Melbourne's Greek community at 600,000 - meaning almost one in five people were of Greek heritage.
This is not backed by the Greek consulate, which says 300,000 would be a more reliable number, and maybe 600,000 for all Australia.
The "official" website estimates there are 450,000 Greeks in New York and 300,000 in Chicago - but Australian Greeks say the number should be closer to 250,000 for New York and maybe slightly fewer in Chicago.
A 2017 quote from Victorian Premier Daniel Andrews refers to the claim without making it:
Melbourne is often described as the third largest ‘Greek city’ in the world
Similarly ABC Radio reported:
It’s claimed that Melbourne has the third biggest Greek population of any city in the world (after Athens and Thessalonica).
Issues to bring to bear on any question:
- What does "Greek" mean? Greek-speaking? Greek heritage? How many generations do we allow before "Greek" becomes meaningless?
- Related to the former: is the Greek-heritage population of Chicago competitive with that of Melbourne?
I'd answered a related question on Quora, which will help answerers get started:
It isn’t immediately obvious from the zip file [of the 2016 Australian Census results] what’s going on, but with perseverance, it turns out that 162,103 people from the Greater Melbourne Area claim Greek ancestry, and 36,758 of them have both parents born in Australia.