Create shop buildings that have a curve?

[LastJedi]

Hi so I've been wondering, how do people go about creating shop buildings that have a curve to them? Like I'm talking about a classic western town hall such as this little beauty:

 

[Bullethead]

That's probably 3 separate buildings that overlap enough to hide the gaps between them. Each face of the whole combined building is a separate "building" as far as the editor is concerned. This is one of the main tricks to making cool stuff.