Keystone (architecture)

In both cases it is the final piece placed during construction and locks all the stones into position, allowing the arch or vault to bear weight.

[citation needed] Old keystones can decay due to weathering and vibration, a condition known as bald arch.

Following Giulio Romano, Mannerist architects of the 16th century often designed arches with enlarged and slightly dropped keystones, as in the "church house" entrance portal at Colditz Castle.

Numerous examples are found in the work of Sebastiano Serlio, a 16th-century Italian Mannerist architect.

"[7] Ezra Taft Benson, the 13th president of the Church of Jesus Christ of Latter-day Saints, said it "is my prayer that the Book of Mormon may become the keystone of our lives.