2007
SH2824 : Mynydd Cilan Triangulation Station
taken 18 years ago, near to Cilan Uchaf, Gwynedd, Wales
This is 1 of 4 images, with title starting with Mynydd Cilan in this square

Mynydd Cilan Triangulation Station
English tourists gather round the Mynydd Cilan trig at 117m above sea level. Hell's Mouth Beach can be seen in the background.
Trig points were a tool to give surveyors a frame of reference for surveying the UK in the days before electronic positioning aids were available (GPS etc). Typically, a trig point is a concrete post set on a high point such as a hill with a metal disc inset in the top which you can put your theodolite in. The trig point is at an accurately surveyed and documented position so you can survey other stuff relative to one or more trig points.
from Link
Trig points were a tool to give surveyors a frame of reference for surveying the UK in the days before electronic positioning aids were available (GPS etc). Typically, a trig point is a concrete post set on a high point such as a hill with a metal disc inset in the top which you can put your theodolite in. The trig point is at an accurately surveyed and documented position so you can survey other stuff relative to one or more trig points.
from Link
