900 # (empty) fire lined safe for anything not under my immediate control. I don't need to bolt it down, You would need a tow truck to move it when loaded down with guns.
The doors are very heavy on those things and there have been people seriously hurt from a safe tipping over ontop of them. Granted it is a rare thing, but Sh@t happens. Plus If you are not home who is to say the thieves won't use one of those moving dollies to wheel it right out the door, guns and all. The guy that delivered ours also bolted it down.
There are holes in the bottom of the safe.
I bought a concrete rated drill bit, bolts and the concrete anchors for them and washers.
Drill the hole in the concrete for the anchors (I did this after the safe was in place) place the anchors in the holes and bolt the safe down using the bolts and washers.
Mine is not bolted down but is in a spare bedroom closet. We have no kiddies running around here that might try and tip it over on themselves so I haven't been in a hurry to do the bolt thing yet. As with all valuables, the guns are best kept in the safe when not in use. All but the few pistols I keep handy for home security.