1) There's the Free Google Sketchup 8, but you would need to learn the Program, which could take some time
http://www.sketchup.com/download/gsu.html.
2) There are thousands of Google Sketchup models in Google warehouse. http://sketchup.google.com/3dwarehouse/
You need Reallusion's 3DXchange Program for 1) & 2), to Import Sketchup models into iClone.
3) Mark's Tutorial HERE; http://www.youtube.com/watch?v=J0GQXwKXvMc&feature=player_embedded will get you started using iClone's 3DBlocks / Architecture. He uses free Textures from CGTextures HERE; http://www.cgtextures.com/
I have CGTextures. I sugggest you create a Custom Library for eg; all doors etc first, by Importing them into individual iClone New Projects, cutting-out the bits you don't want etc; via the Texture UV Settings.
IMO, you can build what you like using his Tut, by adding more floors, walls, windows, doors etc from Architecture & CGTextures, using the Scale Gizmo etc..
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New Pinhead Website & Project to be announced in September 2015
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