Nicola wrote:
I also want to create curved beams an colums to support my walls inside my green hill.
Nicola:
You should be able to create a custom profile of the curved column (as seen in elevation), then use this Custom Profile (see Profile Manager) with a short length of Wall for each column. Short regular walls can be curved (in plan) for the curved beams.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David