Hi hi anon! That would be the magic of hood deco. 😀 The only actual lot in the picture is the one I was playing – the skating rink. The other buildings are conversions of assorted TS3 rabbit holes and Late Night deco buildings by Delonariel and CuriousB. I also have this mod which allows hood deco to be placed on lots – allowing me to overlap deco buildings with my lots to give the illusion of a densely populated city. 😀
I hope this helps!