keystone

architecture

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Last updated

June 30, 2026

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In architecture, a keystone is the wedge-shaped stone placed at the apex of an arch. It is crucial because it locks the other stones, or voussoirs, into place, thereby stabilizing the entire structure.12

Beyond its literal architectural meaning, "keystone" is also used metaphorically to describe something essential that supports a larger system or concept. This could be a fundamental principle, a vital species in an ecosystem (known as a keystone species), or a foundational element upon which other things depend.123

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…central voussoir is called the keystone. The point from which the arch rises from its vertical supports is known as the spring, or springing line. During construction of an arch, the voussoirs require support from below until the keystone has been set in place; this support usually takes the form…
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…central voussoir is called the keystone. The point from which the arch rises from its vertical supports is known as the spring, or springing line. During construction of an arch, the voussoirs require support from below until the keystone has been set in place; this support usually takes the form…
Read More