If you have more questions that aren't answered in rule book, Sirlin's ruling doc (http://www.sirlin.net/rules/), or these forums, I'd recommend posting a short summary of your question in the Thread's title, like: "Is the Base considered a Building?"
That will help people with the same question find the thread, and also help people know if are able to answer your question.
It loses all its level. I would strongly suggest you to carefully read the rulebook. These are very basic questions about things clearly explained in the rules.
To be fair, the point about the base being a building is arguably hidden in an awkward spot. You should read it in your first read-through, but might have trouble explicitly trying to look it up at a later point.