In message , Ian Jelf
writes

When the Millennium Exhibition ("The Dome") at North Greenwich was open
there was supposed to be a place in the grounds where the Meridian was
marked. In *many* visits, I never managed to find it!

5th photo down at: http://www.waller.co.uk/family/dome2.htm
(and see the map near the top - it is to the NW of the Dome, close to
the river).
--
Paul Terry