This city is populated by Goombas. They seem to found a bigger place to live. Their building structures is mushroom shaped.
However, if you try to tick them off, they are now considered as monsters (or they form an angry mob for that matter):
Goomba
Paragoomba
Spikey Goomba
Spike ParaGoomba
Gloomba
ParaGloomba
Spikey Gloomba
Spike ParaGloomba
Hyper Goomba
Hyper ParaGoomba
Hyper Spikey Goomba
Headbonk Goomba