Keystone (architecture)

Sculpted vault keystone in church of Virgin Mary in Chełmno

In architecture, a keystone is the stone at the top of an arch. It is the supporting element for the entire arch— without it the arch would collapse. All the wedge-shaped stones of the arch (or vault) are called voussoirs.

A notched keystone was also the logo of the Pennsylvania Railroad, which operated throughout the northeastern and midwestern United States, Pennsylvania being known as the "keystone state."

In the Bible the parable which referred to the "stone that the builders rejected" is the "head cornerstone," or "keystone." There is no direct translation of keystone from the idiomatic terms in ancient Aramaic, Hebrew, and Greek (presumably, there were no "keys" in those times, or the term had not been yet applied as widely as it is today.)

See also

* Forms in architecture
* List of classical architecture terms
* Pennsylvania Railroad