Image: Where it all began! (geograph 2651652)

Description: This cannon embedded in the ground just by the Northern Perimeter Road of London Heathrow Airport marks the north western end of General Roy's original base line for setting out the Ordnance Survey triangulation of Great Britain in 1784. The plaque on the base was put in place in 1926 to mark the 200th anniversary of General Roy's birth. The south eastern end of the base line is in Roy Grove at Hampton, on the other side of what was at the time Hounslow Heath
Title: Where it all began! (geograph 2651652)
Credit: From geograph.org.uk
Author: Rod Allday
Permission: Creative Commons Attribution Share-alike license 2.0
Usage Terms: Creative Commons Attribution-Share Alike 2.0
License: CC BY-SA 2.0
License Link: https://creativecommons.org/licenses/by-sa/2.0
Attribution Required?: Yes