There's another Washington Monument that you've probably never heard of, and it's adorably tiny and apparently shy.
Hidden away in Washington, D.C., underneath a manhole close to the actual monument, "Bench Mark A" is a control point used by surveyors to help the National Geodetic Survey maintain government map accuracy, according to Atlas Obscura.
This marker has been around since the 1880s and was actually placed on the surface of the ground, fully visible to passersby. At that time, you could also spot parts of the Washington Monument's foundation (see the photo below).
In an interview with Atlas Obscura, NGS modernization manager Dru Smith shared some history on the mini monument.
“All the surveys we’ve done, going back to the early 1900s, have used it,” Smith said. “Geodetic control points provide starting points for any map or measurement. It has to be more accurate than any measurement you do on top of it, so we pick things that tend to be extremely stable.”
This particular control point lives just south of the monument and is 12-feet in height. Before the manhole cover, it was covered in a brick chimney and later completely buried. If you want to see this curiosity in real life, talk to a ranger in the area who can direct you to it.