Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Scaling the Washington Monument Twice in a Century

While many people have enjoyed the view from the top of the Washington Monument in Washington, D.C., only a handful have experienced it from the outside. But it was an on-the-job perk for engineers of the National Institute of Standards and Technology (NIST) who made two trips during the 20th century—albeit 65 years apart—to the pinnacle of the capital’s best-known icon.

The first time was in October 1934 when engineers from the National Bureau of Standards (NBS, the predecessor to NIST) took advantage of scaffolding erected during the monument’s 50th anniversary cleaning and restoration project to carefully examine the gold-plated, platinum-tipped lighting rods and the aluminum cap at its apex. Ironically, the impetus for the obelisk’s major overhaul—and the reason for the scaffolding—came from NBS as well. Earlier in the year, an inspection of the monument’s base by NBS building stone specialist Daniel W. Kessler revealed that a poor distribution of the structure’s 73,663 metric tons (81,200 short tons) created hollow spaces and cracks. His solution was to redistribute the weight of the lower section by filling in the hollows with more elastic mortar than originally used.

Two men sit on scaffolding and examine the tip of the Washington Monument.
National Bureau of Standards engineer William M. Greig (left) and an unidentified man examine the aluminum tip and lighting rods at the top of the Washington Monument in 1934.
Credit: Library of Congress

Three score and five years after the agency’s initial visit to the summit of the Washington Monument, NIST engineers returned there with a new mission: help the National Geodetic Survey (NGS, a part of the National Oceanic and Atmospheric Administration, or NOAA) make the most-accurate-to-date measurement of the landmark’s height. A 1998 to 2001 restoration project once again surrounded the Washington Monument with scaffolding and provided NGS with the opportunity to temporarily place a Global Positioning System (GPS) receiver atop the pyramid cap. NIST engineers designed, built and installed a special mounting that rigidly held the receiver in place and helped pinpoint the GPS signal.

NIST Engineer stands on scaffolding at the top of the Washington Monument
NIST engineer David E. Ward stands next to the Global Positioning System (GPS) receiver and its NIST-designed special mounting atop the Washington Monument in 1999. The NIST device helped scientists from the National Geodetic Survey make GPS-accurate measurements of the obelisk’s height.
Credit: National Oceanic and Atmospheric Administration

The resulting measurement set the monument’s height at 169.26 meters (555 feet, 3-5/8 inches), only 3.8 centimeters (1.5 inch) off from the historically declared figure obtained with traditional surveying methods. It also is less than 1 centimeter (0.4 inch) different from the most recent NGS survey performed when scaffolding was erected around the monument so that repairs could be made following the 2011 D.C.-area earthquake.

Did You Know...?

  • A view of the ground from the top of the Washington Monument
    Looking down at the top of the Washington Monument, a spot visited twice by NIST engineers in the last century.
    Credit: National Park Service
    The tubular steel scaffolding for the Washington Monument’s 1934-1935 restoration project was the highest ever constructed up to that time. The erection and dismantling of the scaffolding cost three-and-a-half times more than the cleaning, painting and repair work.
  • Unfortunately, engineers and masonry workers weren’t the only ones making use of the scaffolding. In December 1934, someone stole 107 of the 170 gold-plated and platinum-tipped lightning rods from the top of the monument. The loss (or gain for the thief) was estimated at around $900 in 1934 dollars ($16,400 in 2017 dollars).
  • Construction on the Washington Monument began in 1848, and by 1854, it had reached a height of 48 meters (156 feet). Political squabbling and a lack of funds then stalled the project, leaving an unfinished landmark as a national embarrassment for the next 22 years. The structure was finally completed on Dec. 6, 1884, when an aluminum tip was placed atop the capstone—the same section that would be examined 50 years later by NBS engineers.

    – Michael E. Newman

    Created June 20, 2017, Updated February 8, 2019