Geograph - photograph every grid square

The bench mark is to be found on Cross Keys House (#21 Queen Street). For a wider view SU1430 : Cross Keys House, Salisbury and for more information about the bench mark Link
A bench mark is an Ordnance Survey arrowhead sign found on walls, bridges, churches and specially erected triangulation pillars where the altitude above sea-level has been accurately measured by surveyors. The arrowhead points to a horizontal line above it which marks the exact altitude.
With rivets and pivots there is no datum (horizontal line) cut, the pointed-to horizontal surface defining the datum height.