A quoin is a masonry block found at the corner of a building that can be an important part of the structure, or could serve a purpose more aesthetic than anything else. Quoins, or cornerstones, are often used in brick buildings to provide a structurally sound base to bear load for the bricks and to give the impression of a solid corner, instead of the corner created from the smaller brickwork.
Quoins are traditionally made from some form of stone or bricks, but can be made from a wide variety of materials, include wood. The historic quoins of buildings are often kept as a marker of where the building used to stand and will sometimes have the date of construction etched into them.
Quoins can be an attractive part of many different types of custom home plans. An experienced home designer can help you determine if this element is right for you.