In the aftermath of Judgment Day, we fled to the Exclusion Zone and sought refuge underground. This is what is left of our fallen civilization.

The Spiral-Locked Letters ofElizabeth I and Mary, Queen of Scots

https://www.bl.uk/eblj/2021articles/pdf/ebljarticle112021.pdf

Mary, Queen of Scots, sealed her final missive with an intricate spiral letterlock

https://arstechnica.com/science/2021/12/mary-queen-of-scots-sealed-her-final-missive-with-an-intricate-spiral-letterlock/