{"id":1695,"date":"2023-04-18T00:00:00","date_gmt":"2023-04-18T00:00:00","guid":{"rendered":"https:\/\/osmaps.com\/discover\/guides\/what-is-a-trig-pillar\/"},"modified":"2026-04-17T12:30:21","modified_gmt":"2026-04-17T12:30:21","slug":"what-is-a-trig-pillar","status":"publish","type":"post","link":"https:\/\/osmaps.com\/discover\/guides\/what-is-a-trig-pillar\/","title":{"rendered":"What is a Trig Pillar or Trig Point ?"},"content":{"rendered":"\n\t\t<header id=\"block_89fc65207551bfd7669b7b1e4d4312fe\" class=\"SingleHero skip-lazy default\">\n\n\t\t\t<div class=\"container\">\n\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<ul class=\"SingleHero__categories\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<li>\n\t\t\t\t\t\t\t\t<a href=\"https:\/\/osmaps.com\/discover\/activities\/uk-hiking\/\" class=\"category\">\n\t\t\t\t\t\t\t\t\tHiking\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<li>\n\t\t\t\t\t\t\t\t<a href=\"https:\/\/osmaps.com\/discover\/activities\/map-reading\/\" class=\"category\">\n\t\t\t\t\t\t\t\t\tMap Reading\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<li>\n\t\t\t\t\t\t\t\t<a href=\"https:\/\/osmaps.com\/discover\/tag\/trig-pillars\/\" class=\"category\">\n\t\t\t\t\t\t\t\t\tTrig Pillars\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t\t\t\t<\/ul>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<h1 class=\"SingleHero__title\" >\n\t\t\t\t\t\tWhat is a Trig Pillar or Trig Point ?\t\t\t\t\t<\/h1>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<div class=\"row justify-content-center align-items-center SingleHero__author\">\n\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"col-auto name\">\n\t\t\t\t\t\t\t\tBy Jonathan Elder\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t<p class=\"SingleHero__meta\">\n\t\t\t\t\t<span>\n\t\t\t\t\t\tPublished on \t\t\t\t\t\t<time datetime=\"2023-04-18T00:00:00+00:00\" itemprop=\"datePublished\">April 18, 2023<\/time>\n\t\t\t\t\t<\/span>\n\n\t\t\t\t\t<span class=\"dot\"><\/span>\n\n\t\t\t\t\t3 min read\t\t\t\t<\/p>\n\n\t\t\t\t<div class=\"SingleHero__thumbnail\">\n\t\t\t\t\t\n\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"1920\" height=\"485\" src=\"https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982.jpg\" class=\"attachment-hd size-hd wp-post-image\" alt=\"trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982\" srcset=\"https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982.jpg 1920w, https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982-300x76.jpg 300w, https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982-1024x259.jpg 1024w, https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982-768x194.jpg 768w, https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982-1536x388.jpg 1536w, https:\/\/osmaps.com\/discover\/wp-content\/uploads\/2024\/03\/trig-point-pillar-project-hero2.2459c66550e35ba20830f8037c980982-1376x348.jpg 1376w\" sizes=\"auto, (max-width: 1920px) 100vw, 1920px\" \/>\t\t\t\t<\/div>\n\n\t\t\t<\/div>\n\t\t<\/header>\n\n\t\n\n\n\t\t<article id=\"block_2c9ec1cc79b6b58c0c5e88fdf5b54fcb\" class=\"Universal Universal--post c-small default pt-default pb-default mt-none mb-none    \" >\n\t\t\t<div class=\"container\">\n\n\t\t\t\t\n\t\t\t\t<div class=\"InnerBlocks\">\n\t\t\t\t\t<span class=\"lead\"><\/span>\n\n\t\t\t\t\t\n\t\t\t\t\t\n\n<h2 class=\"wp-block-heading\" id=\"h-trig-pillars-aka-trig-points-in-the-uk\">Trig Pillars aka Trig Points (in the UK) <\/h2>\n\n\n\n<p>The trig pillar was first used in the retriangulation of Great Britain on 18 April 1936. With over 6500 built, they were vital in map making. Here&#8217;s everything you need to know about trig pillars including 10 great trig point walks.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-what-are-they\">What are they?<\/h2>\n\n\n\n<p>Trig pillars, also known as trig points or&nbsp;triangulation pillars,&nbsp;are columns made of cast concrete or cemented stone. They are typically four foot tall, with a large part of the pillar buried below the surface.<br><br>The iconic trig pillar was designed by Brigadier Martin Hotine in 1935, with the first pillar put in place in 1936. Hotine designed them to triangulate (separate) Great Britain into a network of triangles, and accurately map the land.<br><br>His design also provided a solid base for theodolites \u2013 a precision instrument used by survey teams to improve the accuracy of the readings they obtained.<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/osmaps.com\/discover\/site\/uploads\/images\/2023%20Blog\/trig-point-pillar-project-dublin-mountains.jpg\" alt=\"What is a trig pillar or trig point? Trig Pillar Dublin Mountains\"\/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-why-they-were-important\">Why they were important?<\/h2>\n\n\n\n<p>In the early 20th century, Britain saw a phase of rapid development after the Great War. The systems in place at the time couldn\u2019t support the mapping necessary to monitor the changes.<br><br>Ordnance Survey implemented a new reference process. 6,500 + trig pillars were installed across the country, at specific points with recorded coordinates and point of elevation (their height). Many trig pillars are located on hilltops, for better visibility.<br><br>Once in place, on a clear day surveyors could see at least two other trig points from their own. Then, careful measurements of the angles between other trig points triangulated the lands of Great Britain. Positions of all land boundaries, roads, railways, bridges, and other infrastructure could be accurately plotted by the network.<br><br>The trig pillars helped to map Great Britain, and enabled Ordnance Survey to produce paper maps and mapping data that helped you find this pillar!<\/p>\n\n\n\n<div class=\"images-with-captions\">\n    <div class=\"image-with-caption\">\n        \n        <img decoding=\"async\" src=\"https:\/\/osmaps.com\/discover\/site\/uploads\/images\/2023%20Blog\/trig-point-pillar-project-mam-tor-snow.jpg\" loading=\"lazy\" alt=\"Mam Torr trig pillar\">\n        \n        <p>Mam Torr trig pillar<\/p>\n    <\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-mapping-today\">Mapping today<\/h2>\n\n\n\n<p>80+ years later and trig pillars are now almost obsolete. Time and technologies have moved on, with use of aerial images, drones, satellites, and even a country-wide positioning system that has mapped Great Britain down to centimetre accuracy.<br><br>Trig pillars remain, no longer shaping maps, but they\u2019re a beacon for outdoors lover. A location with great views and photo opportunities.<br><br>And a reminder of our history.<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/osmaps.com\/discover\/site\/uploads\/images\/2023%20Blog\/trig-point-pillar-project-mam-tor.jpg\" alt=\"Mam Torr trig pillar - What is a trig pillar or trig point?\"\/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-fun-facts-about-trig-pillars\">Fun facts about Trig Pillars<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>From every trig pillar, you should be able to see two others.<\/li>\n\n\n\n<li>Trig Pillars are sometimes referred to as \u2018Hotine Pillars\u2019.<\/li>\n\n\n\n<li>The trig pillar was first used in the retriangulation of Great Britain on 18 April 1936.<\/li>\n\n\n\n<li>6,500+ trig pillars were built, but hundreds have been lost to housing developments, farming, coastal erosion, and other causes.<\/li>\n\n\n\n<li>Trig pillars were included on Bill Bryson\u2019s list of favourite British items in his 2015 book \u2018The Road to Little Dribbling.\u2019<\/li>\n\n\n\n<li>Ben Nevis has the highest trig pillar; the lowest is Little Ouse, at -0.533m below sea level, in Cambridgeshire.<\/li>\n\n\n\n<li>The brass fitting on the top of a pillar is known as a \u2018Spider\u2019.<\/li>\n<\/ul>\n\n\n\n<div class=\"images-with-captions\">\n    <div class=\"image-with-caption\">\n        \n        <img decoding=\"async\" src=\"https:\/\/osmaps.com\/discover\/site\/uploads\/images\/2023%20Blog\/trig-point-pillar-project-theodolite.jpg\" loading=\"lazy\" alt=\"Theodolite\">\n        \n        <p>Theodolite<\/p>\n    <\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-10-of-our-favourite-trig-pillar-walks\">10 of our favourite trig pillar walks <\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Back Tor (538m),&nbsp;Upper Derwent Valley &#8211;&nbsp;Peak District&nbsp;&#8211; <a href=\"https:\/\/explore.osmaps.com\/route\/1189886\/country-walking-back-tor--lost-lad-derbyshire\">10 mile \/ 16km walk&nbsp;<\/a><\/li>\n\n\n\n<li>Bein Narnain (927m),&nbsp;Succoth&nbsp;&#8211;&nbsp;Loch Lomond &amp; the Trossachs&nbsp;&#8211; <a href=\"https:\/\/explore.osmaps.com\/route\/15790518\/trail-magazine-april-2023--beinn-narnain--ime-loch-lomond--the-trossachs\">8 mile \/&nbsp;13km walk<\/a>&nbsp;<\/li>\n\n\n\n<li>Selworthy Beacon&nbsp;(309m),&nbsp;Selworthy &#8211;&nbsp;Exmoor National Park&nbsp; &#8211;<a href=\"https:\/\/explore.osmaps.com\/route\/8631884\/country-walking-selworthy-beacon--bossington-hill-somerset\"> 5.3 mile \/ 8.6km&nbsp; walk<\/a><\/li>\n\n\n\n<li>Ramsey Island (136m) &#8211;&nbsp;Pembrokeshire Coast &#8211; <a href=\"https:\/\/explore.osmaps.com\/route\/12113536\/islandeering-ramsey-island-circular-walk\">4.6 mile \/ 7.4km walk<\/a><\/li>\n\n\n\n<li>Moel Wyn (771m), Croesor &#8211;&nbsp;Snowdonia\/Eyri &#8211; <a href=\"https:\/\/explore.osmaps.com\/route\/518386\/trail-magazine-moelwyn-mawr\">8.3 miles \/ 13.4km walk<\/a><\/li>\n\n\n\n<li>Hindhead (273m) &#8211;&nbsp;Surrey Hills &#8211;<a href=\"https:\/\/explore.osmaps.com\/route\/3798457\/the-outdoor-guide-the-devils-punchbowl-walk-surrey-hills\"> 3.5 mile \/ 5.5km walk<\/a><\/li>\n\n\n\n<li>Wrekin (407m),&nbsp;Telford &#8211;&nbsp;Shropshire Hills &#8211; <a href=\"https:\/\/explore.osmaps.com\/route\/8036498\/country-walking-the-wrekin-shropshire\">7.5 mile \/ 12km walk<\/a><\/li>\n\n\n\n<li>Chaipaval (366m),&nbsp;Isle of Harris &#8211;&nbsp;South Lewis, Harris and North Uist National Scenic Area &#8211;&nbsp;<a href=\"https:\/\/explore.osmaps.com\/route\/1428470\/country-walking-toe-head-highland\">9.4 mile \/ 15km walk<\/a><\/li>\n\n\n\n<li>Shaklesborough (454m),&nbsp;Baldersdale &#8211;&nbsp;North Pennines &#8211; <a href=\"https:\/\/explore.osmaps.com\/route\/2263775\/country-walking-shacklesborough-county-durham\">6.4 mile \/ 10.2km walk<\/a><\/li>\n\n\n\n<li>Beeston Hill (64m), Sheringham &#8211;&nbsp;Norfolk Coast &#8211;&nbsp;<a href=\"https:\/\/explore.osmaps.com\/route\/8036508\/country-walking-sheringham--cromer-norfolk\">9.2 mile \/ 15km walk<\/a><\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image\"><a href=\"https:\/\/osmaps.com\/discover\/guides\/hiking-for-beginners-a-complete-guide\/\"><img decoding=\"async\" src=\"https:\/\/getoutside39507958bf.blob.core.windows.net\/blobgetoutside39507958bf\/discover\/wp-content\/uploads\/2024\/06\/copy-of-the-beginners-guide-to-hiking-1000-x-300-px.png\" alt=\"beginners guide to hiking\"\/><\/a><\/figure>\n\n\n\n<p>Want to find out more about getting out into the hills and mountains and finding some of our wonderful OS Trig Points? Read our <a href=\"https:\/\/osmaps.com\/discover\/guides\/hiking-for-beginners-a-complete-guide\/\" target=\"_blank\" rel=\"noreferrer noopener\">Hiking For Beginners Guide<\/a><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\t\t\t\t\t\t\t\t\t<\/div>\n\n\t\t\t\t\n\t\t<div class=\"MetaShare\">\n\n\t\t\t<button id=\"likeButton\" data-nonce=\"50b75bdf00\" data-postid=\"1695\" class=\"Button Button--default Button--icon likeButton\"><span class=\"likeButtonText\">Like this guide<\/span><svg width=\"21\" height=\"20\" viewBox=\"0 0 21 20\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n<path fill-rule=\"evenodd\" clip-rule=\"evenodd\" d=\"M10.4947 3.09742C8.5448 1.39335 5.66108 1.04464 3.42166 2.95804C0.999337 5.02773 0.647396 8.5134 2.56291 10.9783C3.29002 11.9139 4.70917 13.3196 6.07302 14.6069C7.45283 15.9092 8.82946 17.1399 9.50834 17.7411C9.51258 17.7449 9.51691 17.7487 9.5213 17.7526C9.58512 17.8092 9.66457 17.8796 9.74074 17.937C9.83194 18.0057 9.96286 18.0909 10.1377 18.1431C10.3701 18.2124 10.62 18.2124 10.8524 18.1431C11.0272 18.0909 11.1581 18.0057 11.2493 17.937C11.3255 17.8796 11.405 17.8092 11.4688 17.7526C11.4732 17.7487 11.4775 17.7449 11.4817 17.7411C12.1606 17.1399 13.5373 15.9092 14.9171 14.6069C16.2809 13.3196 17.7001 11.9139 18.4272 10.9783C20.3353 8.52288 20.0377 5.01032 17.5597 2.95074C15.2954 1.06872 12.4424 1.3927 10.4947 3.09742Z\" fill=\"#186571\"\/>\n<\/svg>\n<\/button>\n\t\t\t<div class=\"row justify-content-center MetaShareSocial\" aria-label=\"Share\">\n\t\t\t\t<div class=\"col-auto\">\n\t\t\t\t\t<a href=\"#\" role=\"button\" aria-label=\"X\" class=\"Button Button--default MetaShareSocial__button MetaShareSocial__button--x\" id=\"share-twitter\">\n\t\t\t\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"24\" height=\"24\" viewBox=\"0 0 24 24\"><g transform=\"translate(-173 238)\"><path d=\"M18.9.75h3.68l-8.04,9.213L24,22.5H16.594l-5.8-7.6L4.156,22.5H.474l8.6-9.854L0,.75H7.594L12.837,7.7ZM17.61,20.291h2.039L6.486,2.843H4.3Z\" transform=\"translate(173 -237.625)\" fill=\"currentColor\"\/><\/g><\/svg>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"col-auto\">\n\t\t\t\t\t<a href=\"#\" role=\"button\" aria-label=\"facebook\"  class=\"Button Button--default MetaShareSocial__button MetaShareSocial__button--f\" id=\"share-facebook\">\n\t\t\t\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"24\" height=\"24\" viewBox=\"0 0 24 24\"><g transform=\"translate(-89 238)\"><path d=\"M14.186,24V13.2h3.279L18,8.4H14.186V6.062c0-1.236.032-2.462,1.759-2.462h1.749V.168A19.34,19.34,0,0,0,14.671,0C11.5,0,9.508,1.989,9.508,5.64V8.4H6v4.8H9.508V24Z\" transform=\"translate(89 -238)\" fill=\"currentColor\" fill-rule=\"evenodd\"\/><\/g><\/svg>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\n\t\t\t<div id=\"likeCount\" class=\"likeCount\">Liked by <span id=\"likeCountValue\">31<\/span> users<\/div>\n\n\t\t\t\n\t\t\t\t<hr class=\"MetaShare__hr\" \/>\n\n\t\t\t\t<div class=\"MetaShareAuthor\">\n\n\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t<p class=\"MetaShareAuthor__name\">\n\t\t\t\t\t\t\tBy Jonathan Elder\t\t\t\t\t\t<\/p>\n\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"MetaShareAuthor__desc\">\n\t\t\t\t\t\t\t<p>Jonathan helps run the OS Shop and GetOutside, and in his free time can be found walking, playing computer games or, in the winter, falling off mountains with a plank of wood strapped to his feet.<\/p>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\n\t\t\t\n\n\t\t<\/div>\n\n\t\t\t\t<\/div>\n\t\t<\/article>\n\t","protected":false},"excerpt":{"rendered":"<p>The trig pillar was first used in the retriangulation of Great Britain on 18 April 1936. With over 6500 built, they were vital in map making. Here&#8217;s everything you need to know about trig pillars including 10 great trig point walks.<\/p>\n","protected":false},"author":1,"featured_media":1694,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[398],"activities":[90,36],"locations":[],"class_list":["post-1695","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-trig-pillars","activities-uk-hiking","activities-map-reading"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>What is a trig pillar? | OS Maps Discover<\/title>\n<meta name=\"description\" content=\"The trig pillar was first used in the retriangulation of Great Britain on 18 April 1936. 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With over 6500 built, they were vital in map making. 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