Astoria, a neighborhood in northwestern Queens, has significant Greek history and influences. According to Wikipedia, in the 1960s it had the largest Greek population outside of Greece.
When I went to Astoria to look for signs of Greek in mid-2010, I inquired of passers-by where I might find a cluster of Greek places. What I kept hearing was that the concentration of Greeks was not what it used to be, that a lot of signs were now in English, and that things were just more spread out. Three different people sent me in three different directions.
While I did not encounter giant swathes of Greekness, I still found plenty of signs of a continuing Greek presence in the community: Greek lettering, Greek business names, and Greek products.