Does anyone know how to adjust the distance that you can view while in Blender? The Age I'm working on isn't excessively large, but I can only see a finite distance in 3D view. I've been through the official Blender.org wiki and can't find anything referring to this.
I want to see everything in one window, but if I zoom back just a little bit, most of my terrain becomes invisible. No matter what I try, I can't see the entire age at once.

It as though the software has a preset view distance. Also, when I try to render a pic all that shows up is the world color (unless the camera is very, very close to an object).
Any ideas?