A Tile Improvement is a special kind of structure that takes up an entire Minecraft chunk. (16x16 blocks). You can only build as many tile improvements as allotted to your Town Level. To get more tile improvements, you will have to upgrade your town. All tile improvements are destroy-able in war and must be defended.
Some tile improvements have special requirements,which are as follows:
The Trade Outpost must be built on top of a Trade Good on land.
The Fishing Boat must be built on top of a Trade Good on water.
The Cottage requires a Granary to produce its money.
The Windmill requires a Farm to plant crops onto that will actually grow.
Bakery
Butchery
Cottage
Farm
Pasture
Windmill
Strategic Outpost
Strategic Ship
Trade Outpost
Fishing Boat
Merchant Outpost
Merchant Ship