This map showcases all the FBM type of trig points found in the UK that we've successfully imported into our database.

Locations which are not marked with an icon may be available to place a new cache if you wish! Just head on over to our New Request form to get started.

An FBM trig point (Fundamental Benchmark) is a highly precise survey marker used for establishing the UK's national mapping grid. Unlike standard trig pillars, FBMs are low-lying, stable concrete or stone blocks with a brass bolt or plate marking the exact point. They were crucial for measuring elevation and the Earth's curvature, providing a foundation for accurate mapping.

Important to note: the locations displayed for "Ye Ole Survey Monument Caches" represent the trig point itself, not the hidden geocache.

Map Key:

YOSM Locations

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Pillar

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Bolt

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Rivet

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Cannon

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Surface Block

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Intersected Station

Buried Block

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FBM

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Disc

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Cut

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Berntsen

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Concrete Ring

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Active Station

Brass Plate

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Block

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Pipe

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Spider

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Fenomark

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Curry Stool

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Platform Bolt

Unknown/Other

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All Trig Points

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Archived

These maps were last updated on 21 February 2025