The Washington Monument is now almost 10 inches shorter, though that's not because it's actually shrunk, the AP reports. The change in height, to be announced today, is due to a shift in how the monument is measured: "It is just where you start from," says an official with the National Geodetic Survey, which, according to its website, addresses matters like "latitude, longitude, elevation, shoreline information, and their changes over time." The new measurement puts the monument's height at 554 feet, 7 and 11/32 inches. It used to be 555 feet, 5 and 1/8 inches, making it the world's tallest structure when it was finished in 1884. The brass markers thought to have been used in the original measurement that year are now 9 inches underground; they may once have been on the surface, the AP reports.
What's more, there's a plaza at the site that wasn't originally there. "It's clear that what was ground level has changed over the years," adds NGS official Dru Smith, meaning the original measurement was done with "incredible accuracy." The height itself has changed a tiny bit, however, up top. The monument's point is now a bit rounder than it once was, likely because of lightning strikes. "We were able to determine about 3/8 of an inch had been melted off from the very top," says Smith. (Read more Washington Monument stories.)