Well I am guessing that you have already found it, but in case someone else comes looking, it is the Build Your Own City mod, http://www.nexusmods.com/skyrim/mods/50097/?tab=2&navtag=http%3A%2F%2Fwww.nexusmods.com%2Fskyrim%2Fajax%2Fmodfiles%2F%3Fid%3D50097&pUp=1