If not pasture breeding, stallions are best housed in their own individual paddock with access to a stall or within close proximity to their stall. It is recommended that fences around a stallion paddock be at least 5 feet tall and constructed of sturdy material. A stallion may test the fence. It is also best not to house stallions in adjacent paddocks or pasture sharing a common fence line. They will fight over the fence, and that could lead to injury.
Stallions should be housed in solid-walled stalls made of wood or cement block. The front of the stall should be solid half way up and then have some type of grate, expanded metal, etc., to promote ventilation. A window on the back wall is appropriate if properly and safely installed. The following link is to the Midwest Planning Service Horse Facilities Handbook. It will provide further information.