10/19/2026
Indiana Limestone Keystones
Keystones are the wedge-shaped stones set at the top of a masonry arch, also called capstones. As the final piece placed during construction, a keystone locks the surrounding stones into position and carries the structural load of the wall above the opening. That's still their job today, but keystones are just as often used on their own, as a decorative accent above a window or door where there's no structural arch at all.
In either application, the keystone is typically sized larger or shaped more distinctly than the surrounding stones, which is exactly what makes it read as a focal point rather than just another piece of trim. It's a small architectural detail that carries a lot of visual weight, giving an opening a finished, high-end look without adding much cost or complexity to the job.