A Stone Behemoth Gate costs 900 stone, 900 wood, and 900 thatch for the gateway and 450 stone, 450 wood, and 450 thatch for the gate itself for a total of 1350 stone, 1350 wood, and 1350 thatch. A Stone Behemoth Gate is 7 units wide and 12 units high giving a total area of 84 wall units. Stone walls cost 40 stone, 20 wood, and 15 thatch. Stone Walls must be placed on foundations. Stone Fence Foundations cost 15 stone, 10 wood, and 10 thatch. So a 7 unit wide and 12 unit high section made from stone walls would cost 7 * (F + 12 * W) where F is the resources for the foundation and W is the resources for the wall. This comes out to 3465 stone, 1750 wood, 1330 thatch for the same area of wall. The Behemoth Gate approach saves 2115 stone, 400 wood, and only cost 20 more thatch vs the normal wall approach. Therefore the Behemoth Gate is a more economical way to build a wall.
Not so fast...
The main purpose of a wall is to keep dinos out. While it would seem at first glance that the gates are clearly more econmoical you must ask how high does the wall really need to be to serve it's purpose? It turns out a wall on a flat surface needs to be only 2 units high to stop even large dinos like Brontos or Rexes. So even though a Behemoth Gate does a better job at covering area, in most cases it does the same job at stopping dinos as a 2 unit high wall. An no matter how high a wall is it will never stop flying intruders so a wall is never a particularly solid investment. So how much does a 2 unit high 7 unit wide Stone Wall cost? The equation becomes 7 * (F + 2 * W) for a total of 665 stone, 350 wood, and 280 thatch. That's a saving of 685 stone, 1000 wood, and 1070 thatch over the Behemoth Gate approach for every 7 units of coverage. Stone Walls start to break even with Behemoth Gates only above 4 units high which according to various sources is enough to stop even Gigas.
Cost isnt the only factor. The main purpose of a gate is to let dinos in. As such if the gates are opened or destroyed dinos can pass freely through. This is as much a liability as an asset. Reinforced Dinosaur gates have a health rating of 12500 for a wall section 5 units wide. That's 2500 health per unit of width. Whereas the Stone Walls have a health of 10000 for each wall unit. That's 4 times the health for the same width. The smaller size of the wall pieces provide the advantage. If a piece of the wall is destroyed it only opens up 1 unit wide gap. It's much easier to hit a large target like the Reinforced Behemoth gate with several cannon balls than it is to hit a particular unit of wall with several cannon balls. Since the wall breaks in smaller sections, it's also less expensive to repair a given break. A gate is in fact the most vulerable part of a wall. The more gates there are, the weaker the walls will be.
Visibility is a two way thing. The harder it is to look in on your base the harder it is to look out of it as well. If your entire wall is 12 units high any lookout towers need to be at least that high to observe attackers. And again, a flying scout can see over walls of any height so walls are never a good way to ensure privacy. Enclosed buildings are the only things that can really offer privacy.
Being 7 units wide a Behemoth Gate does not work well if the wall is going up or down a hill and many gaps will be left under the gate that have to be patched with extra stone walls. 1 unit wide walls match the curvature of the terrain better and don't leave gaps. Gates should only be built on flat surfaces.
Wow, great guide. Thanks :)