@hannah230 They wanted it to be like Asian culture, but they also wanted a big early 20th century city-type feel. So they chose to make it sort of like New York, but culture-wise (mostly clothing, style, and also some of the music) they tried to keep it Asian-type.
I love the fact that they could put a lot of different cultures into the city though, that was a nice touch because it felt like a real city.
And yes the buildings were definitely based off of real buildings. Like Aang Memorial Island is the Statue of Liberty and that one building that looks like the Eiffel Tower.
“Zuko. You must look within yourself, to save yourself from your other self. Only then, will your true self reveal itself.”
–Zuko imitating Uncle Iroh