Thank you for your help. Actually, the main castle buildings don't have interiors, it is a hollow shell. The detail is on the outside. As for polygon reduction, yes, I do use Cinema version 6, and there are polygon 'optimizing' features available, but they do very little for my model, and in many areas actually do a great deal of damage. In fact a lot of my model is composed of 'instance' duplications, which are supposed to reduce the number of polygons. But after all that effort, I'm still left with 31,722 polygons, and a total of 2,001 objects. Funny thing is that my first castle model had half these quantities and made it into all 3D software with ease. Just can't understand why this building is so different. Maybe I shouldn't have used 'instances', as I've never used them before.