4.Lighthouse
Lighthouses are pretty secure, again with only one entrance (which usually can be incredibly bolted and secured) you shouldn't have too many problems with intruding zombies or killer humans. A lighthouse gives you height. You'll be able to see right around your location, lighthouses are often pretty isolated too, meaning, again, no silly zombies can be lurking outside your front door. There is also places to supply your water, food and other supplies too.