Huge city on world map.

Ok, so... I'm working on a game.
This is the basics of my cliche story...

 Humans live on surface of planet.
 Super tech people live in floating cities.

Super tech come down, and give the humies tech as a give. Humies then use gift to wage war with the Super techs. The super techs have given up war for so long they don't have any weapons, but the humies do.
The humie's go from sword and castle, to big cities with cars in weeks.

How would I map a HUGE city on the world map? I don't want to just spam the town tile, and I tried using diffren't walls to make little buildings... Halp plz.

You could make it bigger using paint. :*

I might give it a shot. How big do you want it?

Wait no I won't. Do it yourself.

...I think you need a custom tileset for this. ;-;
Irock please halp him