Your zombie survival plan

[Stan]

Use their fear of loud noises and raw meat to my advantage.
Get it? Because zombies could be literally anything? Eh?

The fact that I wantnto give Log! Energon cream means things.

[Arni]

The fact that I wantnto give Log! Energon cream means things.

All I can do is lock the doors.  

[DochSavage]

I noticed that some of the castle designs include and depend on moats or other water barriers.
Those only work if zombies can't walk, unbreathing, right under the water (and protected from attack by said water) up to a random spot on your beach or even start burrowing under the submerged walls.

Oops.

If your castle is sitting on solid rock, with sheer cliffs all the way from the seabed to the ramparts, I'd think you'd be good.  Any equivalent structure of reinforced concrete should also work well.  Modern Skyscrapers could work well; particularly with skybridges that can be isolated.

Heck, the freaking Pentagon would be an awesome hardpoint.