Trig point

What are Triangulation (trig) Points (pillars)?

'Trig points', 'Triangulation Points' or 'Triangulation Pillars' are concrete pillars, usually about 4 feet high and were built from 1936 onwards by surveyors at the Ordnance Survey to begin the retriangulation of Great Britain. They are mostly found on the highest points of hills or mountains, but not always, as they need to be where other pillars are visible.

They give you that satisfying feeling, when you've slogged your way up a mountainside, that you are there... you can touch them and have your photo taken by them, to show that you did it!