How to build Outside?

[Kobra19971]

I might have missed it when the game was describing it but how do I create buildings outside like the Well or Stable? I see the build button but there isn't a restriction like money or resources I need to pay nor does the build button work. Is there something I missed or is this a bug?

[Mumelum]

you have to upgrade until the cellar, then you get a dialog to build outside.