OS Benchmark Archive
2018 marked 25 years since the last traditionally-cut arrow style Ordnance Survey benchmark were carved.
There were over 500,000 benchmarks created. On the map you will see that they are largely concentrated in urban areas and mostly along roads or on the side of buildings and walls.
Zoom in to see each benchmark's details. Use the locator tool, top right, to find your closest example.
Read the OS blog about benchmarks:ordnancesurvey.co.uk/blog/2018/05/25-years-since-last-benchmark/