I rent. I don't have a basement at my disposal. My safe (a liberty) is in my bedroom (behind a closet door). If I owned my house and had a basement, I would put it in the basement. If I buy the house I live at now, my safe will go to the basement (very cool and dry). If I buy the house I will add on to it though-think rebar 1 foot thick walls and exterior grade doors with deadbolts between the world and my safe.
That's a perfect place, 2 years in the future though. Put it in the basement (cool and dry). Keep it hidden-why draw attention to your $10,000 (or more) gun collection? If you can bolt it to the floor do so! If there is a door between your safe and the rest of the world, replace it with an exterior grade door (preferably steel) with a dead bolt or two. Then write down every serial number and hide them in you bedroom safe (with your insurance, birth certificate, passport, deed to the house, etc).