“Secure” as in “fortify it against zombies and potentially other threats”

Or as in “I can get to it and lay some sort of claim to it”

Because if it’s the former, we probably need to put some restrictions on the scenario. That’s really the hard part of this and we’re just assuming we can do it, and your best bet is probably to secure as big of an area as possible. A city, a country, a whole hemisphere, or hell, the entire world or the solar system if we’re being really silly.

If we’re going with the latter, where we find a building or property of some kind and call “dibs” and the rest of it is up to us

I think a tech school is a pretty good bet, at least thinking of my local tech schools.

They have some fully stocked workshops with pretty much any tools and materials you could need- carpentry, plumbing, automotive, electrical, etc.

Maybe some kind of medical program, so probably a decent amount of meds and first aid equipment, in addition to whatever is in the nurse’s office.

A culinary program, so you have a well equipped kitchen and probably a decent amount of food on-hand.

Maybe it even has some sort of agricultural program with some farming equipment, maybe even some ready-to-go planted crops and possibly livestock.

Most schools are fairly secure with limited entrances and locking doors often they have backup generators and maybe even solar these days (odds are any school with a decent electrical program at least has a few solar panels kicking around somewhere) and you have the tools and maybe the materials there to further fortify it as needed.

And it probably has some pretty beefy fire suppression systems since you have teenagers playing with welders and industrial stoves/ovens.

Some college campuses might be as good or better for the same reasons, with the added benefits of there probably being some purpose-made living quarters, but they’re usually less compact, which has its plusses and minuses, more land to grow crops and such but harder to secure.

And if the apocalypse hits while school is in session, you have a bunch of young, hopefully reasonably-healthy people already on-hand to do some of the hard work if like me you’re not quite as spry as you used to be.

Walmart or similar has food, tools, guns, ammo, chemicals, and the building can be secured via steel shutters.