I was recently called upon to help a friend empty a storage container at a self-storage facility. I've moved house so many times that it's pretty much second nature to me, and I can Tetris pack a truck or car like no-ones business.
What struck me, at my first visit to a self storage facility was the wide open space that it covered, and how nondescript it was. From the outside, beyond the high fence the unadorned corrugated walls of the facility offer little indication of what lays within, and also blocks off almost any of the lines of sight into the premises, other than via the coverable gate.
The other thing that struck me was the size of the site. There were two distinct warehouse sized buildings, the main one was two floors in size.
In the building we were in there were 40 storage lockers to a corridor, and three corridors, upstairs, and single set of 40 below, with road access. Two sets of metal stairs permitted access, one fright lift. The lockers didn't reach the ceiling. on the ground floor or on the first floor. This gives both clearance for ambient lighting, and reduces fire risks.
The floors were laminated chipboard over a steel grid frame, perhaps not the most structurally sound substrate, but cheep and easy. Each locker we individually roller-doored and padlocked, and offered full enclosure, and were approximately 3m tall, by 4m wide and 1.5m deep. When you do the math, that is a lot of cubic meter storage in one of these places.
Why does any of this matter?
This place screamed safehouse to me.
potentially filled with a variety of trash and/or treasures
The upper areas were spacious, airy and well lit even on a cloudy day by the skylights. The floor was a good 4-5m off the street level thanks tot he steel girder legs and there were no motion or light exposing side windows.
The cross-building connector bridges gave a look-down view over the central driveway, again, without being exposed to the street, and offered more covered and lit areas. I could imagine hanging gardens doing really well here, fed by rainfall collected from the wide flat roofs.
The whole structure, baring the floors was sheet steel and girder, if you discount the polycarbonate sunroof sheeting. I can imagine that it would probably weather a great number of environmental disasters fairly well (apart from tornado strike perhaps).
A potential source of loot, (and looting, parties, lets be fair), and lacking in basic infrastructure, this is however the making of a modern day walled citadel.
Let the walking dead, the floods or plagues come, this kind of facility might make a good refuge in a urban environment.
Unless you are trapped in one with an angry alien, perhaps.