: with the outer fortifications out of our way, it's time to worry about the city in the center.
A: Elevation exception!; if your base is to be built on top of a large mesa or mountain thing, then the top of the base elevation should be topped with walls as well. These should have towers equipped with extremely long rang weapons, anti air turrets (Just in case ^^;
) and telescopes and sensors of every kind so you can see what the problem is when the stupid alarm goes off for the tenth time that day.
If your fortress is on ground level with the outer fortifications, slap on an extra lair of walls with high towers topped with walkways and like I said before, anti air batteries.
: And on to the structuring of the city within. Build multiple levels if possible so that if the bottom floors fall your people can go up and lock the doors. The city should have carefully constructed roads so that locking of one might defend a large portion of the city. Use walls and heavy doors in abundance, and bridges.
A good chunk of your stronghold should be underground if it can be done. If you're on VERY high ground, you could have room for an underground power plant, a waste recycling facility, and perhaps hanger bays built into the side of the cliffs, if they're sheer enough. Tiered tunnels would also be valuable as a place to fall back to if the zombie managed to take over the top of your precious settlement (Not bloody likely if you've followed this guide! XD)
Be aware though, that a huge system of underground zones would be a wonderful place to hide an insurrection or a black market. While a black market wouldn't be much of a problem, an insurrection would be a very bad thing indeed, unless the leader has enough sense to carry it out in a clever way so that the inner fighting wouldn't have an impact on the business of keeping the braindead things out. Still not good though!! -.-
: No stronghold lasts long unless it has enough supplies to keep the people inside alive. This can be done a few ways.
A: Have brave people venture into infected towns and cities looking for supplies and goods.
B: If there's room above ground, build some kind of farm there. Forget the disagreements of various morons; they're all dead and not so very gone right now. GM food is the best way to keep up a good flow of food from inside. If you don't like the idea, remember the alternative; Starving and eventually having your rotting carcasses munched upon bye a load of walking dead bodies. if there weren't any such walking dead, you could possibly avoid it, but not right now
If there's no room above, you can construct a hall of sorts underground, with lighting to replicate sunlight, and a few meters of soil in the floor, and grow your stuff there.
: The electronics and stuff need ways to run. You can use wind power if you're up high enough to catch the wind, or just use spinning wheels to gather static electricity, or manufacture batteries. solar power is also a viable option if you have someone who can manufacture solar panels. forget nuclear power, it's too dangorous to place nuclear material in the middle of a dense population.
: Use radio, or find some way to host your own personal wireless internet. Anything goes, as long as you can communicate. If you find a few survivors who are expert at communiations, you're ditto.
Bah, I'll write more tomorrow, about preserving human history and knowledge, what buildings and stuff to have in your town, and about schooling future generations to fill places left bye skilled people you might recruit once they're gone.