(A response to this video)
What makes a city thrive is, essentially, the thought of Environment, People and Culture.
For a start, you MUST have HUGE city-parks, all throughout the city, as well as Trees lining EACH AND EVERY street. OF COURSE the city MUST be highly walkable (meaning: not car-oriented, but Pedestrian-oriented), PREFERABLY with NO private cars at all and with an EXCELLENT Public Transportation System, both within the city AND out of it, connecting it to all other major areas surrounding it; an excellent international airport, located about 40~60 KM away and connected to the city-center by a fast train, is a very big help there, too, as well as LOTS of community-gardens, where the locals may grow their own food.
However, for a city to actually BE a city, you do also need to encourage (mostly financially, via generous tax-reductions, though not only) the thriving of MANY Cafe`s, all throughout the city, at EACH AND EVERY neighbourhood, as well as a large network of city Libraries, Cinemas, Concert-Halls, Theaters and so on. Without ANY of these elements, a city is just not.
And, of course, a few universities, colleges of Arts and Humanities and some fine hospitals shall do A LOT to elevate a city's status as well.