Do you know of those uh, for the lack of a better word, 'curves' atop of castles, towers & walls? Well, They are not mere decorations, they have a purpose. They are called Machicolations.
So, I've built machicolations into my castle-home & I've put it to use. Unlike that one episode in the last season of Game of Thrones, you know, since castles are meant to protect people & not the other way around.
So, zombies are invading & this is what they did in Game of Thrones.
(They went outside the castle & fought them head-on, losing most of their people).
And here is what they should have done.
Now If I can only get my hands on a lava bucket...