The Mill is a Unique Structure you can add to your backyard in Skyrim: Hearthfire

How to build Mill in Skyrim Hearthfire[edit]

The Mill can only be added to the Heljarchen Hall in The Pale. It cannot be added to other houses.

You should have the option to build the Mill from the Carpenter's Workbench once you have added a door to your house.

The Mill is found under the MISC tab in the Carpenter's Workbench

Materials[edit]

2x Sawn Log

2x Quarried Stone

2x Iron Fittings