The Washington Monument is a stone tower in Washington, D.C., built to honor George Washington, the first president of the United States. It is 169 meters (555 feet) tall. It has the shape of an obelisk, a tall four-sided pillar that narrows as it rises and ends in a small pyramid.

Size

The National Park Service, which cares for the monument, gives its height as 555 feet 5 1/8 inches (169.29 meters). That figure was reported in 1885 by Lt. Col. Thomas Lincoln Casey, the Army engineer who finished the monument. Each side of the base is 55 feet (16.8 meters) wide, and the height was chosen to be about ten times that width.

In 2013 and 2014, the National Geodetic Survey, a U.S. government agency, measured the monument again with GPS and other modern survey tools. It found a height of 554 feet 7 11/32 inches (169.046 meters), with an uncertainty of about 1 millimeter. That is about 25 centimeters (10 inches) less than the older figure.

Most of the difference comes from where the measurement starts. The 2014 survey followed today's international standard for measuring buildings, which starts about 22 centimeters (9 inches) higher than the point Casey probably used. Weathering and lightning have also rounded off the monument's aluminum tip, which is about 1 centimeter (3/8 inch) shorter than it was.

Size comparisons

A Saturn V rocket, 111 meters (363 feet) tall, would reach about two-thirds of the way to the top.
The Great Pyramid of Giza was about 147 meters (481 feet) tall when it was built, about 23 meters (74 feet) shorter than the monument.
About 100 people 1.7 meters (5 feet 7 inches) tall, standing on one another's heads, would reach the top.
Laid on its side, the monument would be about as long as one and a half American football fields, end zones included.
The Eiffel Tower, 330 meters (1,083 feet) tall, is almost twice as tall.

Building the monument

A private group, the Washington National Monument Society, raised money for the monument and chose a design by the architect Robert Mills. The cornerstone was laid on July 4, 1848. By 1854 the monument was 156 feet (47.5 meters) tall, but the society had run out of money, and work stopped for more than 20 years.

In 1876, Congress took over the project, and the U.S. Army Corps of Engineers, led by Casey, finished it. The first quarry's marble was no longer available, so the upper part was built with stone from other quarries. The stones have weathered differently, and a change in color about a third of the way up is still visible.

On December 6, 1884, workers set the capstone, and Casey placed a small aluminum tip on top. The finished monument was the tallest building in the world, taller than Cologne Cathedral in Germany. It was dedicated on February 21, 1885.

Inside the monument

An elevator takes visitors to an observation deck 500 feet (152 meters) up, at the base of the monument's pointed top. There are 896 steps from the ground to that level, but the stairs have been closed to the public since 1976. The inside walls hold 193 memorial stones, given in Washington's honor by people, groups, cities, states and countries.

On August 23, 2011, a magnitude 5.8 earthquake cracked stones and loosened mortar in the monument. The repairs, which lasted until 2014, used scaffolding that let surveyors reach the very top. That made the new height measurement possible.

Sources

Frequently Asked Questions. Washington Monument, National Park Service, 2024.
History & Culture. Washington Monument, National Park Service, 2022.
2011 Earthquake. Washington Monument, National Park Service, 2019.
2013–2014 Survey of the Washington Monument. NOAA Technical Report NOS NGS 51, National Geodetic Survey, 2015.
What Was the Saturn V? (Grades 5-8). NASA, 2010.
The Pyramids and Temples of Gizeh. W. M. Flinders Petrie. Field & Tuer, 1883.
Introduction to Giza. Giza Project, Harvard University.
2026 Official Playing Rules of the National Football League. National Football League, 2026.
From 300 to 330 meters: the story of the Tower's height. Société d'Exploitation de la Tour Eiffel.

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