You must turn on the browser location services to get the route from your current location to the sign, and the distance (as the crow flies) from your current location to the sign.
After activating location services, refresh the page.
On the sign:
Greenwich Meridian Marker 1750-1851 This pillar was built in 1798 to help astronomers align the Observatorys meridian telescope in the building behind you. This telescope defined what was then the Greenwich Meridian established in 1750 and was kept accurately positioned by sighting a metal marker on the top of the pillar. In1851 George Airy, 7th Astronomer Royal, installed a new telescope and move the Greenwich Meridian a little to the east, to its current position. Between 1920 and 1950 this pillar was used as a support for a night-sky camera.