How to change the layout of my city?

The longer you survive the more likely it gets that you need to make adjustments to your village.
Zombies attack from all directions, so you need strong defenses on all sides. You also want to dictate their path so you can take them out more easily.

To move or rotate a building, simply tap on it during the daytime and you can move it around. If it turns red then it is blocked by another building.
If it's green, you are all good and the building will stay at its new spot.