Quote - I have all sorts or building and ruins props but have never worked out a good terrain prop to set them on... any advise for a free or affordable setting for large scale props like building? I just can't fit them even with multiple cyclorama props and such so I am looking for a realistic large scale terrain. I bought RDNA MacroCosm but I can't get a good setting from it.

I'm not sure what you're looking for, exactly.  One thing you might be able to use is Terragen.  It's free for personal/non-commercial use and you could use it to generate foreground/background textures.  http://www.planetside.co.uk/terragen/

With the right textures, you could use this freebie to make a decent groundplane for large scales.  http://www.sharecg.com/v/26480/Poser/Luna-Fayes-Morphing-Planes

IIRC, there's also http://www.sharecg.com/v/26572/Poser/LF-Morphing-Walls  Which you might be able to use to create a nice, semicircular backplane.  IIRC, the back wall is very large and morphable so you can curve it to whatever angle you wish.  Increase the y-axis, give it a higher-resolution map and you're in business.

There's some other freebie "morphing terrains" around as well.  I have a couple, I think.  I just don't remember the names atm.

The most important thing for your purposes is that they aren't all simply "hills" and have enough room for a building.  BUT, there's no rule that says you can't use more than one.  What about using two?  Use a simple, hi-res flat plane with a texture on it that is close enough to the morphed plane and then position them so they look contiguous.  A bit of fooling around with the lighting, turning off any shadows on the flat plane and you would probably be fine with the edges seeming to blend in decently.  If you needed to cover them up, a few simple flat planes with 2-d pictures of scrub, bushes and such could be placed just in front of them relative to the camera.