What is the "Negative City" in the Garden of Stubborn Cats, by Italo Calvino?

It is said that there was a tome when cats and men shared the same city, "Only few cats remember the times when there was no difference: the streets and the squares of the people were also streets and squares of the cats..." But, as time progressed, cats and men parted. Sure they lived in the midst of each other but the cats could no longer exist side by side. The city of man became unliveable for felines,

"But, already for many generations now, the domestic felines are prisoners of an unlivable city: the streets are uninterruptedly raced by the deadly traffic of the cat-crushing automobiles..."

So the cats sought sanctuaries, away from the concrete monstrosities and motorized contraptions which polluted the air. Marcovaldo finds such a sanctuary in the garden of an old lady who refused to sell her land to developers.

Thank you! So just to be clear, the negative city is the city where humans live?

Yup, it is no longer cat friendly!

how have the city altered the way cats live in the story the garden of stubborn cats ?

How was negative city created ?