Triangulation station

fixed surveying station used in geodetic surveying

A triangulation station is a fixed surveying station, used in surveying.

A trigonometrical station in Hong Kong
A trigonometrical station in the Sierra de Guadarrama, Spain

It may also be known as a triangulation pillar, trigonometrical station, trigonometrical point, trig station, trig beacon or trig point, and sometimes informally as a trig,

The names of triangulation stations vary regionally; they are generally known as trigonometrical stations in North America, trig points in the United Kingdom, New Zealand and Australia, and trig beacons in South Africa; triangulation pillar is the more formal term for the concrete columns found in the UK.