"Keystone"

On late spring evenings, a bright stellar "keystone" is well worth exploring with binoculars or a small telescope.

They say that on any given day, you can learn something new, and recently that happened with me. I was wondering why Pennsylvania is known as "The Keystone State," and now I know what a keystone is. It's a central, wedge-shaped stone at the top of an arch that holds all the other stones in place. While the exact wording cannot be confirmed with absolute certainty, it is believed that in the early 19th century, Pennsylvania was honored with the descriptive phrase, "the keystone in the federal union" and was later referred to as "the keystone in the democratic arch."

There is also a keystone in our current night sky: the Keystone of Hercules.

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https://www.space.com/hercules-keystone-evening-spring-sky.html