Steve has already written about our day over on Shadows and Light and put up some lovely photos.
Here are a few more from me ...
The Greenwich Observatory
Steve standing on the Meridian
Public standards of length. These British Imperial Standards were first mounted outside Greenwich Observatory main gates some time before 1866, to enable the public to check measures of length. The stated length is the distance between the inner faces of the 2 D-shaped studs.
Ceiling of The Painted Hall as seen in a mirror!