The first letter of a sentence must be capitalized as well as the name of a city. If you capitalize the starting 'k' and put a period after 'city', it is a correct sentence.
This is not a correct sentence. It might be used by someone that learned to speak in the inner city, but is not correct.
"It is one of the biggest cities" is correct.
Either "A new global trend has come to the city." or "A new global trend has been brought to the city." are correct.
She moved from a rural area to a heavily populated large city.
That is the correct spelling of the proper noun Toronto (a large Canadian city).
That is the correct spelling of the proper noun Montreal (large city in Canada).
The correct capitalization of proper nouns is: "A waitress in a New York City restaurant brought an Englishman the Soup of the Day."
The bustling metropolis was filled with skyscrapers and traffic.
No. It isn't needed there.
That is the correct spelling for the large city in the US state of Ohio (capitalized), Akron.
There is a large reservoir on the edge of the city that provides water for it.
Key West - the southernmost city in the US - is located in Florida.