# Cornerstone https://en.wikipedia.org/wiki/Cornerstone A **cornerstone** (or **foundation stone** or **setting stone**) is the first stone set in the construction of a [masonry](https://en.wikipedia.org/wiki/Masonry "Masonry") [foundation](https://en.wikipedia.org/wiki/Foundation_(engineering) "Foundation (engineering)"). All other stones will be set in reference to this stone, thus determining the position of the entire [structure](https://en.wikipedia.org/wiki/Construction "Construction").