If you mean in the context as a 'new' built city as in you code in objects to make it look like a city
That ain't always the most easy thing to make the city look good
Due to the boundaries of objects, the walls would be like a cm apart
and it would look
****But if you mean by just adding what you suggested to a city like LLetya or something
Then thats different and pretty easy, though nothing really needs to be added, in my opinion, I think your just being lazy, and you don't feel like making money
So I will help you out here
Ways:
Thieving stalls
Slayer tasks**
King black dragon
If you have 85 slayer, then abyssal demons
Pest control--
Mining
Smithing
Runecrafting
Ways for advanced, geared players:
Nex solo/duo
Godwars solo/duo
Tormented demons
Corporeal beast solo/duo
Thats really about it, spend some time on the first ways, then when you get a decent amount of stats, and money, buy yourself full bandos/armadyl and try your luck at these bosses
Note:
Tormented demons do not hit TOO high, and can be done in full dragon
KBD can be easily done in full dragon
-mario