In which of these can a miniature replica of the Washington Monument be found?

There’s a 12-foot-tall replica of the Washington Monument under a manhole near the actual monument. Known as “Bench Mark A,” this underground oddity is actually a Geodetic Control Point that’s used by surveyors. It’s part of the network of a million control points across the country that helps the National Geodetic Survey (NGS). The NGS is a United States federal agency based in Washington, D.C. that defines and manages a national coordinate system, providing the foundation for transportation and communication, mapping and charting, and a large number of science and engineering applications.

The mini monument was placed in the 1880s as a part of a trans-continental leveling program. The ground level there was much lower at that time, with large parts of the Washington Monument foundation still visible above ground. The mini monument was above ground for a time, before being encased in a brick chimney and buried. Outside of surveying circles, it’s been largely forgotten.