To my flat, actually. Yes, this is a floor plan of my current flat. The problem is it's currently quite empty, so play around with nice ideas and send me a pull request once you're done.
I'm using sweet home 3d, grab a copy at http://www.sweethome3d.com/index.jsp - it's free! Open an issue if you know a better open source tool :-)
Feel free to use this as CC-BY 3.0 The tiles within each .sh3d file might be subject to different licenses.