It's a program by Autodesk; they make AutoCAD, Inventor, and 3DSMax.
Like I said, not really much modeling on my part. In fact, I didn't do any modeling at all except for the house itself. Most of the furniture was pre-loaded, the rest I had to find elsewhere. The whole thing was more difficult that it may seem though, the pictures you see are the result of an entire semester of work. There are other fully furnished rooms I don't have pictures of, unfortunately.