I have a lot of tools, and the first thing I put in my safe wasn't a gun, it was my cutting torches. Someone may break in, and they may cut the safe open, but they won't do it with my own tools!
Or better yet, have the safe (if its permanently installed, which it should be) on its own alarm circuit. My safe has its own alarm on the door which is key controlled so even if the home alarm is not armed the safe is armed, and if the home alarm is armed the safe's alarm circuit can still be disarmed with the key.Security- if you have an alarm system, you want the safe in a part of the home protected by the alarm.
The only problem with putting it in the middle of the building is that even if its a fire safe its probably not going to survive in the middle of your burning house. I have mine on an outside wall (built into the wall, sandwiched all around by studs so being pulled through the wall is not a concern) and the location of it is noted in the hazmat book at the local fire dept, so if there is ever a fire and I am not here, when they check my address to see if there are dangerous materials at this address they will see the note giving the location of the fire safe and know to put a hose on it to keep it coolVisibility- you want it concealed, if possible. Access to an outside wall- you want it as far toward the center of the structure as possible, as smaller safes can be pulled through a wall by a truck and dragged away or loaded and hauled away. And so on.