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All the United Kingdom England London Trafalgar Square Imperial Measurements
AO Edited

Trafalgar Square Imperial Measurements

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

London, England

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Kerry Wolfe
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Imperial measurements.   SUZANNE PLUCKETT/used with permission
The standard for Imperial Measurement.   John Winfield/cc by-sa 2.0
The plaques are within the northern end of the square.   Elliott Brown/cc by 2.0
Imperial standards of length 1876 in Trafalgar Square, London.   Kaihsu Tai/cc by-sa 3.0
Imperial measurements.   SUZANNE PLUCKETT/used with permission
Imperial measurements.   SUZANNE PLUCKETT/used with permission
Imperial measurements.   Collector of Experiences / Atlas Obscura User
Imperial measurements.   CoolCrab / Atlas Obscura User
  SEANETTA / Atlas Obscura User
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The steps up to the National Gallery   jooniur / Atlas Obscura User
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30 feet   Xavixavir / Atlas Obscura User
Trafalgar Square Imperial Measurements   Xavixavir / Atlas Obscura User
Imperial measurements.   SUZANNE PLUCKETT/used with permission
Better than a ruler   Dixontrips / Atlas Obscura User
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Trafalgar Square is a notoriously busy spot, one that is packed with tourists crowding around its famous statues and intriguing attractions. But many of these visitors don’t know that there are pieces of London’s past hidden right under their feet.

A series of plaques are embedded within the northeastern part of Trafalgar Square. Turn your eyes to the wall and the stairs leading toward the National Gallery, and you’ll see various official Imperial measurements—some more familiar than others—that have lain in the square since 1876.

The plaques depicting inches, feet, and yards as measured at 62 degrees Fahrenheit do more than give tourists a crash course on Imperial units (even those who favor the Imperial system may still be perplexed by the plaques for chains, perches, and poles). The Board of Trade installed these markers to preserve the standard units of measurement that were created between 1838 and 1842.

A standards commission overseen by Sir George Airy created three copies of the official units of measurement after a devastating fire in the Palace of Westminster destroyed the old ones. Trafalgar Square isn’t the only place within London to spot these official measurements. You can also find some in the Great Hall of the Guildhall and near the Royal Observatory in Greenwich.

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Hidden History Plaques

Know Before You Go

The plaques are all located along the northern end of Trafalgar Square. Some are set into the wall, while others are embedded in the stairs leading toward the National Gallery. Your best bet for viewing the plaques is early in the morning or later in the evening, when there are fewer people crowding the square.

The measurements run the entire length from east to west on the steps across from the fountains. Please be aware that many of the plaques are now obscured by the outdoor seating of Cafe On The Square, so it may be best to avoid trying to see them during the cafe's opening hours, especially during the summer, when the crowds can make them difficult to see.

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Added By

Kerry Wolfe

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SEANETTA, Xoan, CoolCrab, llcoolsteve...

  • SEANETTA
  • Xoan
  • CoolCrab
  • llcoolsteve
  • Collector of Experiences
  • rbenn250
  • Dixontrips
  • Xavixavir
  • jooniur
  • beefjorky

Published

October 18, 2018

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  • https://www.adventuresofalondonkiwi.com/2013/11/trafalgar-square-unusual-measure-of.html
  • https://londonist.com/london/videos/video-the-imperial-measures-of-trafalgar-square
  • https://untappedcities.com/2013/02/05/london-trafalgar-square-standard-units/
  • https://www.science20.com/florilegium/blog/imperial_units_length_melt_parliament_burns_science_trafalgar_square_london
Trafalgar Square Imperial Measurements
Trafalgar Square
London, England
United Kingdom
51.50835, -0.1277
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