They can also be used to help your military units travel faster. If a road is under water too long, it may deteriorate. Walls Walls provide defense against opponents. Enemy soldiers have to go around or destroy a wall to get through. Walls can also be used to mark boundaries, to hold back river waters, or to build dams along a river.
Walls also block the spread of fire.
Canals Canals are forty foot deep channels for water. They allow you to bring water to drier areas or control the flow of water in other areas. Canals can also be built around residential areas to provide some protection against flooding. Towers Towers are good places to position blob soldiers. They are as high as walls, but stronger.