My group has recently acquired an old guard tower as a base of operations. It's a fixer-upper, so I made a short document with some guidelines on ways to fix it up.
There is a really good "Stronghold Building" guide on DMsGuild:
http://www.dmsguild.com/product/207...ilding-and-customizing-playerowned-structures
But, it's large. So my goal with this document was for it to be short and to-the-point. It's basically like an equipment list, but for buildings.