There are circles in cities, but not (to my knowledge) circular sub-divisions as depicted on the site. That's something I associate with Europe, not America.
In most of America, including Washington D.C., the circles are very quickly ironed back out into grids.
This site claims to create American-style cities, but includes images with radial circles that extend about seven blocks, which is not at all something most people associate with American cities, but do associate with, say, Spain.
The urban density in these images is also more commonly found in Europe than America.
Which is fine! It's a generator for European-style cities, and it's neat! But so far, only low-density western desert cities have anything like 7-ringed wedges like this, and I suspect that most people, like me, didn't know those existed there before this thread.
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In most of America, including Washington D.C., the circles are very quickly ironed back out into grids.